GNOME screen blanking issue on suspend

I am dual-booting Manjaro GNOME (updated) and CachyOS GNOME (updated) on a single desktop machine. I recently connected a new monitor to this machine, a KTC model HT27T27 27" QHD monitor. However, I’m seeing different behavior between the two OSes when it comes to suspending the monitor when the “Blank Screen” timeout is reached.

When running Manjaro: Roughly 50% of the time, when the timeout for screen “blanking” is reached, “blanking” is exactly what happens; i.e., the image of the desktop and whatever else is on it goes away, but the backlight remains on and the power LED remains a steady blue, indicating that the monitor is still in a powered state. When I press a key or move the mouse, the desktop reappears.
The other 50% of the time, the monitor behaves as it should when the screen blank timeout is reached; i.e., the monitor displays a message that the signal is gone and the power indicator changes to a blinking red LED to indicate that the monitor is suspended. (If I touch a key or move the mouse during this period, the behavior is also as expected, i.e., the monitor comes back on and the image is restored.) However, if I do not wake the monitor up with a key or the mouse, at some point within the next several minutes, something happens that changes the power LED back to a solid blue and the backlight comes back on, although there is still no image displayed UNTIL I touch a key or move the mouse.

When running CachyOS: The behavior is exactly as expected 100% of the time; when the timeout is reached, the monitor is powered off until I wake it up with a mouse move or keypress.

I’ve tried letting dmesg and journalctl run on each machine while waiting for the timeouts and waking to happen but no relevant messages were printed; if you want me to try either or both again with specific switches, just let me know the switches you recommend. Below is the output of inxi -Fazy for each OS as well as the /etc/default/grub and mkinitcpio.conf files for each; just let me know if you’d like me to grab any other info.

Any thoughts welcome, TIA.

Here is the output of sudo inxi -Fazy when running Manjaro:

System:
  Kernel: 6.12.12-2-MANJARO arch: x86_64 bits: 64 compiler: gcc v: 14.2.1
    clocksource: tsc avail: acpi_pm
    parameters: BOOT_IMAGE=/boot/vmlinuz-6.12-x86_64
    root=UUID=7fbea43d-7c13-4c07-9c33-dc2f41b840a7 rw quiet splash apparmor=1
    security=apparmor udev.log_priority=3
  Console: pty pts/3 DM: GDM v: 47.0 Distro: Manjaro base: Arch Linux
Machine:
  Type: Desktop System: LENOVO product: 11D5S0H700 v: ThinkCentre M90t
    serial: <filter> Chassis: type: 3 serial: <filter>
  Mobo: LENOVO model: 315F v: SDK0T76538 WIN 3556314468530 serial: N/A
    part-nu: LENOVO_MT_11D5_BU_Think_FM_ThinkCentre M90t
    uuid: 4f4fc482-76b9-11ed-8bd2-77f170af2e00 UEFI: LENOVO v: M2TKT51A
    date: 07/15/2022
CPU:
  Info: model: Intel Core i7-10700 socket: U3E1 bits: 64 type: MT MCP
    arch: Comet Lake gen: core 10 level: v3 note: check built: 2020
    process: Intel 14nm family: 6 model-id: 0xA5 (165) stepping: 5
    microcode: 0xFC
  Topology: cpus: 1x dies: 1 clusters: 8 cores: 8 threads: 16 tpc: 2
    smt: enabled cache: L1: 512 KiB desc: d-8x32 KiB; i-8x32 KiB L2: 2 MiB
    desc: 8x256 KiB L3: 16 MiB desc: 1x16 MiB
  Speed (MHz): avg: 1514 min/max: 800/4800 base/boost: 2900/4800 scaling:
    driver: intel_pstate governor: powersave volts: 0.8 V ext-clock: 100 MHz
    cores: 1: 1514 2: 1514 3: 1514 4: 1514 5: 1514 6: 1514 7: 1514 8: 1514
    9: 1514 10: 1514 11: 1514 12: 1514 13: 1514 14: 1514 15: 1514 16: 1514
    bogomips: 92838
  Flags: avx avx2 ht lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx
  Vulnerabilities:
  Type: gather_data_sampling mitigation: Microcode
  Type: itlb_multihit status: KVM: Split huge pages
  Type: l1tf status: Not affected
  Type: mds status: Not affected
  Type: meltdown status: Not affected
  Type: mmio_stale_data mitigation: Clear CPU buffers; SMT vulnerable
  Type: reg_file_data_sampling status: Not affected
  Type: retbleed mitigation: Enhanced IBRS
  Type: spec_rstack_overflow status: Not affected
  Type: spec_store_bypass mitigation: Speculative Store Bypass disabled via
    prctl
  Type: spectre_v1 mitigation: usercopy/swapgs barriers and __user pointer
    sanitization
  Type: spectre_v2 mitigation: Enhanced / Automatic IBRS; IBPB: conditional;
    RSB filling; PBRSB-eIBRS: SW sequence; BHI: SW loop, KVM: SW loop
  Type: srbds mitigation: Microcode
  Type: tsx_async_abort status: Not affected
Graphics:
  Device-1: Intel CometLake-S GT2 [UHD Graphics 630] vendor: Lenovo
    driver: i915 v: kernel arch: Gen-9.5 process: Intel 14nm built: 2016-20
    ports: active: DP-3 empty: DP-1, DP-2, HDMI-A-1, HDMI-A-2, HDMI-A-3
    bus-ID: 00:02.0 chip-ID: 8086:9bc5 class-ID: 0300
  Display: unspecified server: X.org v: 1.21.1.15 with: Xwayland v: 24.1.5
    compositor: gnome-shell driver: gpu: i915 tty: 254x24
  Monitor-1: DP-3 model: H27T27 serial: <filter> built: 2024 res: 2560x1440
    dpi: 108 gamma: 1.2 size: 620x370mm (24.41x14.57") diag: 685mm (27")
    ratio: 16:9 modes: max: 2560x1440 min: 720x400
  API: EGL v: 1.5 hw: drv: intel iris platforms: device: 0 drv: iris
    device: 1 drv: swrast gbm: drv: iris surfaceless: drv: iris
    inactive: wayland,x11
  API: OpenGL v: 4.6 compat-v: 4.5 vendor: mesa v: 24.3.4-arch1.1
    note: console (EGL sourced) renderer: Mesa Intel UHD Graphics 630 (CML GT2),
    llvmpipe (LLVM 19.1.7 256 bits)
  Info: Tools: api: eglinfo,glxinfo x11: xprop,xrandr
Audio:
  Device-1: Intel Comet Lake PCH cAVS vendor: Lenovo driver: snd_hda_intel
    v: kernel alternate: snd_soc_avs,snd_sof_pci_intel_cnl bus-ID: 00:1f.3
    chip-ID: 8086:06c8 class-ID: 0403
  Device-2: TEAC TASCAM US-16x08 driver: snd-usb-audio type: USB rev: 2.0
    speed: 480 Mb/s lanes: 1 mode: 2.0 bus-ID: 1-1:2 chip-ID: 0644:8047
    class-ID: 0103 serial: <filter>
  Device-3: M-Audio MidiSport 8x8/s Loader driver: N/A type: USB rev: 1.0
    speed: 12 Mb/s lanes: 1 mode: 1.1 bus-ID: 1-3:3 chip-ID: 0763:1031
    class-ID: 0000
  API: ALSA v: k6.12.12-2-MANJARO status: kernel-api with: aoss
    type: oss-emulator tools: alsactl,alsamixer,amixer
  Server-1: PipeWire v: 1.2.7 status: n/a (root, process) with:
    1: pipewire-pulse status: active 2: wireplumber status: active
    3: pipewire-alsa type: plugin 4: pw-jack type: plugin
    tools: pactl,pw-cat,pw-cli,wpctl
Network:
  Device-1: Intel Ethernet I219-LM vendor: Lenovo driver: e1000e v: kernel
    port: N/A bus-ID: 00:1f.6 chip-ID: 8086:0d4c class-ID: 0200
  IF: eno1 state: up speed: 1000 Mbps duplex: full mac: <filter>
  Info: services: NetworkManager, sshd, systemd-timesyncd, wpa_supplicant
Drives:
  Local Storage: total: 3.7 TiB used: 477.86 GiB (12.6%)
  SMART Message: Required tool smartctl not installed. Check --recommends
  ID-1: /dev/nvme0n1 maj-min: 259:0 vendor: TeamGroup model: TM8FP6002T
    size: 1.86 TiB block-size: physical: 512 B logical: 512 B speed: 31.6 Gb/s
    lanes: 4 tech: SSD serial: <filter> fw-rev: SN24998 temp: 18.9 C
    scheme: GPT
  ID-2: /dev/nvme1n1 maj-min: 259:2 vendor: TeamGroup model: TM8FP6001T
    size: 953.87 GiB block-size: physical: 512 B logical: 512 B speed: 31.6 Gb/s
    lanes: 4 tech: SSD serial: <filter> fw-rev: T1102A0L temp: 23.9 C
    scheme: GPT
  ID-3: /dev/sda maj-min: 8:0 vendor: Samsung model: ST1000LM024 HN-M101MBB
    size: 931.51 GiB block-size: physical: 512 B logical: 512 B type: USB
    rev: 3.0 spd: 5 Gb/s lanes: 1 mode: 3.2 gen-1x1 tech: HDD rpm: 5400
    serial: <filter> fw-rev: 0608 scheme: GPT
Partition:
  ID-1: / raw-size: 475.59 GiB size: 467.05 GiB (98.21%)
    used: 74.78 GiB (16.0%) fs: ext4 block-size: 4096 B dev: /dev/nvme1n1p2
    maj-min: 259:4
  ID-2: /boot/efi raw-size: 512 MiB size: 511 MiB (99.80%)
    used: 9.7 MiB (1.9%) fs: vfat block-size: 512 B dev: /dev/nvme1n1p1
    maj-min: 259:3
Swap:
  Kernel: swappiness: 60 (default) cache-pressure: 100 (default) zswap: no
  ID-1: swap-1 type: file size: 30.52 GiB used: 0 KiB (0.0%) priority: -2
    file: /swapfile
Sensors:
  System Temperatures: cpu: 26.0 C pch: 29.0 C mobo: N/A
  Fan Speeds (rpm): N/A
Info:
  Memory: total: 32 GiB available: 31.06 GiB used: 1.45 GiB (4.7%) igpu: 32 MiB
  Processes: 306 Power: uptime: 31m states: freeze,mem,disk suspend: deep
    avail: s2idle wakeups: 0 hibernate: platform avail: shutdown, reboot,
    suspend, test_resume image: 12.41 GiB services: gsd-power,
    power-profiles-daemon, upowerd Init: systemd v: 257 default: graphical
    tool: systemctl
  Packages: 1515 pm: pacman pkgs: 1508 libs: 400 tools: gnome-software,pamac
    pm: flatpak pkgs: 7 Compilers: clang: 19.1.7 gcc: 14.2.1 Shell: Sudo (sudo)
    v: 1.9.16p2 default: Bash v: 5.2.37 running-in: pty pts/3 (SSH)
    inxi: 3.3.37

Here is the /etc/default/grub from Manjaro:

GRUB_DEFAULT=saved
GRUB_TIMEOUT=5
GRUB_TIMEOUT_STYLE=hidden
GRUB_DISTRIBUTOR="Manjaro"
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash apparmor=1 security=apparmor udev.log_priority=3"
GRUB_CMDLINE_LINUX=""

# If you want to enable the save default function, uncomment the following
# line, and set GRUB_DEFAULT to saved.
GRUB_SAVEDEFAULT=true

# Uncomment to disable submenus in boot menu
#GRUB_DISABLE_SUBMENU=y

# Preload both GPT and MBR modules so that they are not missed
GRUB_PRELOAD_MODULES="part_gpt part_msdos"

# Uncomment to enable booting from LUKS encrypted devices
#GRUB_ENABLE_CRYPTODISK=y

# Uncomment to use basic console
GRUB_TERMINAL_INPUT=console

# Uncomment to disable graphical terminal
#GRUB_TERMINAL_OUTPUT=console

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command 'videoinfo'
GRUB_GFXMODE=auto

# Uncomment to allow the kernel use the same resolution used by grub
GRUB_GFXPAYLOAD_LINUX=keep

# Uncomment if you want GRUB to pass to the Linux kernel the old parameter
# format "root=/dev/xxx" instead of "root=/dev/disk/by-uuid/xxx"
#GRUB_DISABLE_LINUX_UUID=true

# Uncomment to disable generation of recovery mode menu entries
GRUB_DISABLE_RECOVERY=true

# Uncomment this option to enable os-prober execution in the grub-mkconfig command
GRUB_DISABLE_OS_PROBER=false

# Uncomment and set to the desired menu colors.  Used by normal and wallpaper
# modes only.  Entries specified as foreground/background.
GRUB_COLOR_NORMAL="light-gray/black"
GRUB_COLOR_HIGHLIGHT="green/black"

# Uncomment one of them for the gfx desired, a image background or a gfxtheme
#GRUB_BACKGROUND="/usr/share/grub/background.png"
GRUB_THEME="/usr/share/grub/themes/manjaro/theme.txt"

# Uncomment to get a beep at GRUB start
#GRUB_INIT_TUNE="480 440 1"

# Uncomment to ensure that the root filesystem is mounted read-only so that
# systemd-fsck can run the check automatically. We use 'fsck' by default, which
# needs 'rw' as boot parameter, to avoid delay in boot-time. 'fsck' needs to be
# removed from 'mkinitcpio.conf' to make 'systemd-fsck' work.
# See also Arch-Wiki: https://wiki.archlinux.org/index.php/Fsck#Boot_time_checking
#GRUB_ROOT_FS_RO=true

Here is the /etc/mkinitcpio.conf from Manjaro (in case it has something to do with a hook, maybe?):

# vim:set ft=sh
# MODULES
# The following modules are loaded before any boot hooks are
# run.  Advanced users may wish to specify all system modules
# in this array.  For instance:
#     MODULES=(usbhid xhci_hcd)
MODULES=(i915)

# BINARIES
# This setting includes any additional binaries a given user may
# wish into the CPIO image.  This is run last, so it may be used to
# override the actual binaries included by a given hook
# BINARIES are dependency parsed, so you may safely ignore libraries
BINARIES=()

# FILES
# This setting is similar to BINARIES above, however, files are added
# as-is and are not parsed in any way.  This is useful for config files.
FILES=()

# HOOKS
# This is the most important setting in this file.  The HOOKS control the
# modules and scripts added to the image, and what happens at boot time.
# Order is important, and it is recommended that you do not change the
# order in which HOOKS are added.  Run 'mkinitcpio -H <hook name>' for
# help on a given hook.
# 'base' is _required_ unless you know precisely what you are doing.
# 'udev' is _required_ in order to automatically load modules
# 'filesystems' is _required_ unless you specify your fs modules in MODULES
# Examples:
##   This setup specifies all modules in the MODULES setting above.
##   No RAID, lvm2, or encrypted root is needed.
#    HOOKS=(base)
#
##   This setup will autodetect all modules for your system and should
##   work as a sane default
#    HOOKS=(base udev autodetect modconf block filesystems fsck)
#
##   This setup will generate a 'full' image which supports most systems.
##   No autodetection is done.
#    HOOKS=(base udev modconf block filesystems fsck)
#
##   This setup assembles a mdadm array with an encrypted root file system.
##   Note: See 'mkinitcpio -H mdadm_udev' for more information on RAID devices.
#    HOOKS=(base udev modconf keyboard keymap consolefont block mdadm_udev encrypt filesystems fsck)
#
##   This setup loads an lvm2 volume group.
#    HOOKS=(base udev modconf block lvm2 filesystems fsck)
#
##   NOTE: If you have /usr on a separate partition, you MUST include the
#    usr and fsck hooks.
HOOKS=(base udev autodetect modconf kms block keyboard keymap consolefont plymouth filesystems fsck)

# COMPRESSION
# Use this to compress the initramfs image. By default, gzip compression
# is used. Use 'cat' to create an uncompressed image.
#COMPRESSION="gzip"
#COMPRESSION="bzip2"
#COMPRESSION="lzma"
#COMPRESSION="xz"
#COMPRESSION="lzop"
#COMPRESSION="lz4"
#COMPRESSION="zstd"

# COMPRESSION_OPTIONS
# Additional options for the compressor
#COMPRESSION_OPTIONS=()

# MODULES_DECOMPRESS
# Decompress kernel modules during initramfs creation.
# Enable to speedup boot process, disable to save RAM
# during early userspace. Switch (yes/no).
#MODULES_DECOMPRESS="yes"

Here is the output of sudo inxi -Fazy when running CachyOS:

System:
  Kernel: 6.13.5-2-cachyos arch: x86_64 bits: 64 compiler: clang v: 19.1.7
    clocksource: tsc avail: acpi_pm
    parameters: BOOT_IMAGE=/boot/vmlinuz-linux-cachyos
    root=UUID=6d9c8edc-c93e-4a0b-830e-4cf9757488b4 rw nowatchdog nvme_load=YES
    zswap.enabled=0 splash loglevel=3
  Console: pty pts/1 DM: GDM v: 47.0 Distro: CachyOS base: Arch Linux
Machine:
  Type: Desktop System: LENOVO product: 11D5S0H700 v: ThinkCentre M90t
    serial: <filter> Chassis: type: 3 serial: <filter>
  Mobo: LENOVO model: 315F v: SDK0T76538 WIN 3556314468530 serial: N/A
    part-nu: LENOVO_MT_11D5_BU_Think_FM_ThinkCentre M90t
    uuid: 4f4fc482-76b9-11ed-8bd2-77f170af2e00 UEFI: LENOVO v: M2TKT51A
    date: 07/15/2022
CPU:
  Info: model: Intel Core i7-10700 socket: U3E1 bits: 64 type: MT MCP
    arch: Comet Lake gen: core 10 level: v3 note: check built: 2020
    process: Intel 14nm family: 6 model-id: 0xA5 (165) stepping: 5
    microcode: 0xFC
  Topology: cpus: 1x dies: 1 clusters: 8 cores: 8 threads: 16 tpc: 2
    smt: enabled cache: L1: 512 KiB desc: d-8x32 KiB; i-8x32 KiB L2: 2 MiB
    desc: 8x256 KiB L3: 16 MiB desc: 1x16 MiB
  Speed (MHz): avg: 800 min/max: 800/4800 base/boost: 2900/4800 scaling:
    driver: intel_pstate governor: powersave volts: 0.8 V ext-clock: 100 MHz
    cores: 1: 800 2: 800 3: 800 4: 800 5: 800 6: 800 7: 800 8: 800 9: 800
    10: 800 11: 800 12: 800 13: 800 14: 800 15: 800 16: 800 bogomips: 92796
  Flags: avx avx2 ht lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx
  Vulnerabilities:
  Type: gather_data_sampling mitigation: Microcode
  Type: itlb_multihit status: KVM: Split huge pages
  Type: l1tf status: Not affected
  Type: mds status: Not affected
  Type: meltdown status: Not affected
  Type: mmio_stale_data mitigation: Clear CPU buffers; SMT vulnerable
  Type: reg_file_data_sampling status: Not affected
  Type: retbleed mitigation: Enhanced IBRS
  Type: spec_rstack_overflow status: Not affected
  Type: spec_store_bypass mitigation: Speculative Store Bypass disabled via
    prctl
  Type: spectre_v1 mitigation: usercopy/swapgs barriers and __user pointer
    sanitization
  Type: spectre_v2 mitigation: Enhanced / Automatic IBRS; IBPB: conditional;
    RSB filling; PBRSB-eIBRS: SW sequence; BHI: SW loop, KVM: SW loop
  Type: srbds mitigation: Microcode
  Type: tsx_async_abort status: Not affected
Graphics:
  Device-1: Intel CometLake-S GT2 [UHD Graphics 630] vendor: Lenovo
    driver: i915 v: kernel arch: Gen-9.5 process: Intel 14nm built: 2016-20
    ports: active: none off: DP-3 empty: DP-1, DP-2, HDMI-A-1, HDMI-A-2,
    HDMI-A-3 bus-ID: 00:02.0 chip-ID: 8086:9bc5 class-ID: 0300
  Display: unspecified server: X.org v: 1.21.1.16 with: Xwayland v: 24.1.6
    compositor: gnome-shell driver: gpu: i915 tty: 254x24
  Monitor-1: DP-3 model: H27T27 serial: <filter> built: 2024 res: 2560x1440
    dpi: 108 gamma: 1.2 size: 620x370mm (24.41x14.57") diag: 685mm (27")
    ratio: 16:9 modes: max: 2560x1440 min: 720x400
  API: EGL v: 1.5 hw: drv: intel iris platforms: device: 0 drv: iris
    device: 1 drv: swrast gbm: drv: iris surfaceless: drv: iris
    inactive: wayland,x11
  API: OpenGL v: 4.6 compat-v: 4.5 vendor: mesa v: 25.0.0-cachyos1.1
    note: console (EGL sourced) renderer: Mesa Intel UHD Graphics 630 (CML GT2),
    llvmpipe (LLVM 19.1.7 256 bits)
  Info: Tools: api: eglinfo,glxinfo x11: xdpyinfo, xprop, xrandr
Audio:
  Device-1: Intel Comet Lake PCH cAVS vendor: Lenovo driver: snd_hda_intel
    v: kernel alternate: snd_soc_avs,snd_sof_pci_intel_cnl bus-ID: 00:1f.3
    chip-ID: 8086:06c8 class-ID: 0403
  Device-2: TEAC TASCAM US-16x08 driver: snd-usb-audio type: USB rev: 2.0
    speed: 480 Mb/s lanes: 1 mode: 2.0 bus-ID: 1-1:2 chip-ID: 0644:8047
    class-ID: 0103 serial: <filter>
  Device-3: M-Audio MidiSport 8x8/s Loader driver: N/A type: USB rev: 1.0
    speed: 12 Mb/s lanes: 1 mode: 1.1 bus-ID: 1-3:3 chip-ID: 0763:1031
    class-ID: 0000
  API: ALSA v: k6.13.5-2-cachyos status: kernel-api
    tools: alsactl,alsamixer,amixer
  Server-1: JACK v: 1.9.22 status: off tools: N/A
  Server-2: PipeWire v: 1.2.7 status: n/a (root, process) with:
    1: pipewire-pulse status: active 2: wireplumber status: active
    3: pipewire-alsa type: plugin tools: pactl,pw-cat,pw-cli,wpctl
Network:
  Device-1: Intel Ethernet I219-LM vendor: Lenovo driver: e1000e v: kernel
    port: N/A bus-ID: 00:1f.6 chip-ID: 8086:0d4c class-ID: 0200
  IF: eno1 state: up speed: 1000 Mbps duplex: full mac: <filter>
  Info: services: NetworkManager, sshd, systemd-timesyncd, wpa_supplicant
Drives:
  Local Storage: total: 3.7 TiB used: 9.47 GiB (0.2%)
  ID-1: /dev/nvme0n1 maj-min: 259:2 vendor: TeamGroup model: TM8FP6001T
    size: 953.87 GiB block-size: physical: 512 B logical: 512 B speed: 31.6 Gb/s
    lanes: 4 tech: SSD serial: <filter> fw-rev: T1102A0L temp: 24.9 C
    scheme: GPT
  SMART: yes health: PASSED on: 3 hrs cycles: 34 read-units: 428,856 [219 GB]
    written-units: 1,688,623 [864 GB]
  ID-2: /dev/nvme1n1 maj-min: 259:0 vendor: TeamGroup model: TM8FP6002T
    size: 1.86 TiB block-size: physical: 512 B logical: 512 B speed: 31.6 Gb/s
    lanes: 4 tech: SSD serial: <filter> fw-rev: SN24998 temp: 19.9 C
    scheme: GPT
  SMART: yes health: PASSED cycles: 33 read-units: 288,577 [147 GB]
    written-units: 1,106,045 [566 GB]
  ID-3: /dev/sda maj-min: 8:0 vendor: Samsung model: ST1000LM024 HN-M101MBB
    family: Seagate SpinPoint M8 (AF) size: 931.51 GiB block-size:
    physical: 4096 B logical: 512 B type: USB rev: 3.0 spd: 5 Gb/s lanes: 1
    mode: 3.2 gen-1x1 sata: 3.0 speed: 3.0 Gb/s tech: HDD rpm: 5400
    serial: <filter> fw-rev: 0608 drive-rev: 2AR20002 temp: 31 C scheme: GPT
  SMART: yes state: enabled health: PASSED on: 2y 144d 0h cycles: 119
Partition:
  ID-1: / raw-size: 477.78 GiB size: 469.22 GiB (98.21%) used: 9.46 GiB (2.0%)
    fs: ext4 block-size: 4096 B dev: /dev/nvme0n1p3 maj-min: 259:5
  ID-2: /boot/efi raw-size: 512 MiB size: 511 MiB (99.80%)
    used: 9.7 MiB (1.9%) fs: vfat block-size: 512 B dev: /dev/nvme0n1p1
    maj-min: 259:3
Swap:
  Kernel: swappiness: 150 (default 60) cache-pressure: 50 (default 100)
    zswap: no
  ID-1: swap-1 type: zram size: 31.06 GiB used: 0 KiB (0.0%) priority: 100
    comp: zstd avail: lzo-rle,lzo,lz4,lz4hc,deflate,842 max-streams: 16
    dev: /dev/zram0
Sensors:
  System Temperatures: cpu: 26.0 C pch: 31.0 C mobo: N/A
  Fan Speeds (rpm): N/A
Info:
  Memory: total: 32 GiB available: 31.06 GiB used: 1.85 GiB (6.0%) igpu: 32 MiB
  Processes: 329 Power: uptime: 4m states: freeze,mem,disk suspend: deep
    avail: s2idle wakeups: 0 hibernate: platform avail: shutdown, reboot,
    suspend, test_resume image: 12.41 GiB services: gsd-power,
    power-profiles-daemon, upowerd Init: systemd v: 257 default: graphical
    tool: systemctl
  Packages: 1046 pm: pacman pkgs: 1040 libs: 318
    tools: gnome-software,octopi,paru,yay pm: flatpak pkgs: 6 Compilers:
    clang: 19.1.7 gcc: 14.2.1 Shell: Sudo (sudo) v: 1.9.16p2 default: Bash
    v: 5.2.37 running-in: pty pts/1 (SSH) inxi: 3.3.37

Here is the /etc/default/grub from CachyOS:

# GRUB boot loader configuration

GRUB_DEFAULT='saved'
GRUB_TIMEOUT='15'
GRUB_DISTRIBUTOR='CachyOS'
GRUB_CMDLINE_LINUX_DEFAULT='nowatchdog nvme_load=YES zswap.enabled=0 splash loglevel=3'
GRUB_CMDLINE_LINUX=""

# Preload both GPT and MBR modules so that they are not missed
GRUB_PRELOAD_MODULES="part_gpt part_msdos"

# Uncomment to enable booting from LUKS encrypted devices
#GRUB_ENABLE_CRYPTODISK=y

# Set to 'countdown' or 'hidden' to change timeout behavior,
# press ESC key to display menu.
GRUB_TIMEOUT_STYLE=menu

# Uncomment to use basic console
GRUB_TERMINAL_INPUT=console

# Uncomment to disable graphical terminal
#GRUB_TERMINAL_OUTPUT=console

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `videoinfo'
GRUB_GFXMODE=auto

# Uncomment to allow the kernel use the same resolution used by grub
GRUB_GFXPAYLOAD_LINUX=keep

# Uncomment if you want GRUB to pass to the Linux kernel the old parameter
# format "root=/dev/xxx" instead of "root=/dev/disk/by-uuid/xxx"
#GRUB_DISABLE_LINUX_UUID=true

# Uncomment to disable generation of recovery mode menu entries
#GRUB_DISABLE_RECOVERY='true'

# Uncomment and set to the desired menu colors.  Used by normal and wallpaper
# modes only.  Entries specified as foreground/background.
#GRUB_COLOR_NORMAL="light-blue/black"
#GRUB_COLOR_HIGHLIGHT="light-cyan/blue"

# Uncomment one of them for the gfx desired, a image background or a gfxtheme
GRUB_BACKGROUND='/usr/share/wallpapers/cachyos-wallpapers/splash.png'
#GRUB_THEME="/path/to/gfxtheme"

# Uncomment to get a beep at GRUB start
#GRUB_INIT_TUNE="480 440 1"

# Uncomment to make GRUB remember the last selection. This requires
# setting 'GRUB_DEFAULT=saved' above.
#GRUB_SAVEDEFAULT=true

# Uncomment to disable submenus in boot menu
GRUB_DISABLE_SUBMENU='false'

# Probing for other operating systems is disabled for security reasons. Read
# documentation on GRUB_DISABLE_OS_PROBER, if still want to enable this
# functionality install os-prober and uncomment to detect and include other
# operating systems.
GRUB_DISABLE_OS_PROBER=false
GRUB_EARLY_INITRD_LINUX_STOCK=''

Here is the /etc/mkinitcpio.conf from CachyOS (in case it has something to do with a hook, maybe?):

# vim:set ft=sh
# MODULES
# The following modules are loaded before any boot hooks are
# run.  Advanced users may wish to specify all system modules
# in this array.  For instance:
#     MODULES=(usbhid xhci_hcd)
MODULES=()

# BINARIES
# This setting includes any additional binaries a given user may
# wish into the CPIO image.  This is run last, so it may be used to
# override the actual binaries included by a given hook
# BINARIES are dependency parsed, so you may safely ignore libraries
BINARIES=()

# FILES
# This setting is similar to BINARIES above, however, files are added
# as-is and are not parsed in any way.  This is useful for config files.
FILES=()

# HOOKS
# This is the most important setting in this file.  The HOOKS control the
# modules and scripts added to the image, and what happens at boot time.
# Order is important, and it is recommended that you do not change the
# order in which HOOKS are added.  Run 'mkinitcpio -H <hook name>' for
# help on a given hook.
# 'base' is _required_ unless you know precisely what you are doing.
# 'udev' is _required_ in order to automatically load modules
# 'filesystems' is _required_ unless you specify your fs modules in MODULES
# Examples:
##   This setup specifies all modules in the MODULES setting above.
##   No RAID, lvm2, or encrypted root is needed.
#    HOOKS=(base)
#
##   This setup will autodetect all modules for your system and should
##   work as a sane default
#    HOOKS=(base udev autodetect modconf block filesystems fsck)
#
##   This setup will generate a 'full' image which supports most systems.
##   No autodetection is done.
#    HOOKS=(base udev modconf block filesystems fsck)
#
##   This setup assembles a mdadm array with an encrypted root file system.
##   Note: See 'mkinitcpio -H mdadm_udev' for more information on RAID devices.
#    HOOKS=(base udev modconf keyboard keymap consolefont block mdadm_udev encrypt filesystems fsck)
#
##   This setup loads an lvm2 volume group.
#    HOOKS=(base udev modconf block lvm2 filesystems fsck)
#
##   This will create a systemd based initramfs which loads an encrypted root filesystem.
#    HOOKS=(base systemd autodetect modconf kms keyboard sd-vconsole sd-encrypt block filesystems fsck)
#
##   NOTE: If you have /usr on a separate partition, you MUST include the
#    usr and fsck hooks.
HOOKS=(base udev autodetect microcode kms modconf block keyboard keymap consolefont plymouth filesystems fsck)

# COMPRESSION
# Use this to compress the initramfs image. By default, zstd compression
# is used for Linux ≥ 5.9 and gzip compression is used for Linux < 5.9.
# Use 'cat' to create an uncompressed image.
#COMPRESSION="zstd"
#COMPRESSION="gzip"
#COMPRESSION="bzip2"
#COMPRESSION="lzma"
#COMPRESSION="xz"
#COMPRESSION="lzop"
#COMPRESSION="lz4"

# COMPRESSION_OPTIONS
# Additional options for the compressor
#COMPRESSION_OPTIONS=()

# MODULES_DECOMPRESS
# Decompress loadable kernel modules and their firmware during initramfs
# creation. Switch (yes/no).
# Enable to allow further decreasing image size when using high compression
# (e.g. xz -9e or zstd --long --ultra -22) at the expense of increased RAM usage
# at early boot.
# Note that any compressed files will be placed in the uncompressed early CPIO
# to avoid double compression.
#MODULES_DECOMPRESS="no"

Mod edit:- Changed topic title for better Search results.

Oops, meant to add, I’ve tried with all GNOME Extensions disabled on both machines, made no difference. Right now each is running only Vitals and Removable Drive Menu.

Oops, one more thing to add; booted a Manjaro Live USB and the monitor suspends as expected, and as it does with CachyOS.