Kernels 5.14 - 5.15 regression?

Starting from kernel 5.14 and 5.15 too, it seems the screen backlight control in keyboard doesn’t work anymore. Tuxedo keyboard installed. Display is Samsung Amoled 4k

inxi --admin --verbosity=7 --filter --width
System:
  Kernel: 5.14.18-1-MANJARO x86_64 bits: 64 compiler: gcc v: 11.1.0
  parameters: BOOT_IMAGE=/boot/vmlinuz-5.14-x86_64
  root=UUID=9c139704-ec02-4583-af7f-c3650112b202 rw ipv6.disable=1
  net.ifnames=0 quiet udev.log_priority=3 nowatchdog
  Desktop: KDE Plasma 5.23.3 tk: Qt 5.15.2 wm: kwin_x11 vt: 1 dm: SDDM
  Distro: Manjaro Linux base: Arch Linux
Machine:
  Type: Laptop System: SANTECH product: PCX0DX v: N/A
  serial: <superuser required> Chassis: type: 10 serial: <superuser required>
  Mobo: SANTECH model: PCX0DX serial: <superuser required> UEFI: INSYDE
  v: 1.07.09TSAS date: 09/14/2020
Battery:
  ID-1: BAT0 charge: 53.5 Wh (79.6%) condition: 67.2/70.7 Wh (95.1%)
  volts: 12.2 min: 11.4 model: Notebook BAT type: Li-ion serial: <filter>
  status: Unknown
Memory:
  RAM: total: 15.45 GiB used: 2.33 GiB (15.1%)
  RAM Report:
  missing: Required tool dmidecode not installed. Check --recommends
CPU:
  Info: 8-Core model: Intel Core i7-10875H bits: 64 type: MT MCP
  arch: Comet Lake family: 6 model-id: A5 (165) stepping: 2 microcode: EA
  cache: L1: 512 KiB L2: 2 MiB L3: 16 MiB bogomips: 73625
  Speed: 958 MHz min/max: 800/5100 MHz Core speeds (MHz): 1: 900 2: 1392
  3: 924 4: 804 5: 817 6: 883 7: 868 8: 866 9: 900 10: 900 11: 900 12: 868
  13: 868 14: 828 15: 828 16: 900
  Flags: 3dnowprefetch abm acpi adx aes aperfmperf apic arat arch_capabilities
  arch_perfmon art avx avx2 bmi1 bmi2 bts clflush clflushopt cmov constant_tsc
  cpuid cpuid_fault cx16 cx8 de ds_cpl dtes64 dtherm dts epb ept ept_ad erms
  est f16c flexpriority flush_l1d fma fpu fsgsbase fxsr ht hwp hwp_act_window
  hwp_epp hwp_notify ibpb ibrs ibrs_enhanced ida intel_pt invpcid
  invpcid_single lahf_lm lm mca mce md_clear mmx monitor movbe mpx msr mtrr
  nonstop_tsc nopl nx ospke pae pat pbe pcid pclmulqdq pdcm pdpe1gb pebs pge
  pku pln pni popcnt pse pse36 pts rdrand rdseed rdtscp rep_good sdbg sep smap
  smep smx ss ssbd sse sse2 sse4_1 sse4_2 ssse3 stibp syscall tm tm2
  tpr_shadow tsc tsc_adjust tsc_deadline_timer vme vmx vnmi vpid x2apic
  xgetbv1 xsave xsavec xsaveopt xsaves xtopology xtpr
  Vulnerabilities: Type: itlb_multihit status: KVM: VMX disabled
  Type: l1tf status: Not affected
  Type: mds status: Not affected
  Type: meltdown status: Not affected
  Type: spec_store_bypass
  mitigation: Speculative Store Bypass disabled via prctl and seccomp
  Type: spectre_v1
  mitigation: usercopy/swapgs barriers and __user pointer sanitization
  Type: spectre_v2 mitigation: Enhanced IBRS, IBPB: conditional, RSB filling
  Type: srbds status: Not affected
  Type: tsx_async_abort status: Not affected
Graphics:
  Device-1: Intel CometLake-H GT2 [UHD Graphics] vendor: CLEVO/KAPOK
  driver: i915 v: kernel bus-ID: 00:02.0 chip-ID: 8086:9bc4 class-ID: 0300
  Device-2: NVIDIA TU116M [GeForce GTX 1660 Ti Mobile] vendor: CLEVO/KAPOK
  driver: nvidia v: 495.44 alternate: nouveau,nvidia_drm bus-ID: 01:00.0
  chip-ID: 10de:2191 class-ID: 0300
  Device-3: Acer BisonCam NB Pro type: USB driver: uvcvideo bus-ID: 1-8:3
  chip-ID: 5986:9102 class-ID: 0e02
  Display: x11 server: X.Org 1.21.1.1 compositor: kwin_x11 driver:
  loaded: modesetting,nvidia alternate: fbdev,nouveau,nv,vesa display-ID: :0
  screens: 1
  Screen-1: 0 s-res: 3840x2160 s-dpi: 192 s-size: 508x285mm (20.0x11.2")
  s-diag: 582mm (22.9")
  Monitor-1: eDP-1 res: 3840x2160 hz: 60 dpi: 284 size: 344x194mm (13.5x7.6")
  diag: 395mm (15.5")
  OpenGL: renderer: Mesa Intel UHD Graphics (CML GT2) v: 4.6 Mesa 21.2.5
  direct render: Yes
Audio:
  Device-1: Intel Comet Lake PCH cAVS vendor: CLEVO/KAPOK
  driver: snd_hda_intel v: kernel alternate: snd_soc_skl,snd_sof_pci_intel_cnl
  bus-ID: 00:1f.3 chip-ID: 8086:06c8 class-ID: 0403
  Sound Server-1: ALSA v: k5.14.18-1-MANJARO running: yes
  Sound Server-2: JACK v: 1.9.19 running: no
  Sound Server-3: PulseAudio v: 15.0 running: yes
  Sound Server-4: PipeWire v: 0.3.40 running: no
Network:
  Device-1: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet
  vendor: CLEVO/KAPOK driver: r8169 v: kernel port: 3000 bus-ID: 42:00.0
  chip-ID: 10ec:8168 class-ID: 0200
  IF: eth0 state: up speed: 100 Mbps duplex: full mac: <filter>
  IP v4: <filter> type: dynamic noprefixroute scope: global
  broadcast: <filter>
  Device-2: Intel Wi-Fi 6 AX200 driver: iwlwifi v: kernel bus-ID: 44:00.0
  chip-ID: 8086:2723 class-ID: 0280
  IF: wlan0 state: down mac: <filter>
  WAN IP: <filter>
Bluetooth:
  Device-1: Intel AX200 Bluetooth type: USB driver: btusb v: 0.8
  bus-ID: 1-14:5 chip-ID: 8087:0029 class-ID: e001
  Report: rfkill ID: hci0 rfk-id: 1 state: down bt-service: disabled
  rfk-block: hardware: no software: yes address: see --recommends
Logical:
  Message: No logical block device data found.
RAID:
  Message: No RAID data found.
Drives:
  Local Storage: total: 931.52 GiB used: 80.81 GiB (8.7%)
  SMART Message: Unable to run smartctl. Root privileges required.
  ID-1: /dev/nvme0n1 maj-min: 259:4 vendor: Samsung
  model: SSD 970 EVO Plus 500GB size: 465.76 GiB block-size: physical: 512 B
  logical: 512 B speed: 31.6 Gb/s lanes: 4 type: SSD serial: <filter>
  rev: 2B2QEXM7 temp: 25.9 C scheme: GPT
  ID-2: /dev/nvme1n1 maj-min: 259:0 vendor: Samsung model: SSD 980 PRO 500GB
  size: 465.76 GiB block-size: physical: 512 B logical: 512 B speed: 63.2 Gb/s
  lanes: 4 type: SSD serial: <filter> rev: 3B2QGXA7 temp: 26.9 C scheme: GPT
  Message: No optical or floppy data found.
Partition:
  ID-1: / raw-size: 426.41 GiB size: 418.71 GiB (98.20%)
  used: 80.81 GiB (19.3%) fs: ext4 dev: /dev/nvme1n1p2 maj-min: 259:2
  label: Manjaro uuid: 9c139704-ec02-4583-af7f-c3650112b202
  ID-2: /boot/efi raw-size: 300 MiB size: 299.4 MiB (99.80%)
  used: 152 KiB (0.0%) fs: vfat dev: /dev/nvme1n1p1 maj-min: 259:1 label: EFI
  uuid: 9208-96D2
Swap:
  Kernel: swappiness: 1 (default 60) cache-pressure: 50 (default 100)
  ID-1: swap-1 type: partition size: 8.01 GiB used: 0 KiB (0.0%) priority: -2
  dev: /dev/nvme1n1p3 maj-min: 259:3 label: Swap
  uuid: 2bdf47c9-bfc9-471a-9b84-361c4467b14a
Unmounted:
  ID-1: /dev/nvme0n1p1 maj-min: 259:5 size: 100 MiB fs: vfat label: N/A
  uuid: A2D7-A2EB
  ID-2: /dev/nvme0n1p2 maj-min: 259:6 size: 16 MiB fs: <superuser required>
  label: N/A uuid: N/A
  ID-3: /dev/nvme0n1p3 maj-min: 259:7 size: 465.15 GiB fs: ntfs label: N/A
  uuid: 568CE7BE8CE796B1
  ID-4: /dev/nvme0n1p4 maj-min: 259:8 size: 511 MiB fs: ntfs label: N/A
  uuid: FA825FD0825F904D
USB:
  Hub-1: 1-0:1 info: Hi-speed hub with single TT ports: 16 rev: 2.0
  speed: 480 Mb/s chip-ID: 1d6b:0002 class-ID: 0900
  Device-1: 1-3:2 info: USB OPTICAL MOUSE type: Mouse
  driver: hid-generic,usbhid interfaces: 1 rev: 1.1 speed: 1.5 Mb/s
  power: 100mA chip-ID: 0000:0538 class-ID: 0301
  Device-2: 1-8:3 info: Acer BisonCam NB Pro type: Video driver: uvcvideo
  interfaces: 2 rev: 2.0 speed: 480 Mb/s power: 500mA chip-ID: 5986:9102
  class-ID: 0e02
  Device-3: 1-10:4 info: Synaptics type: <vendor specific> driver: N/A
  interfaces: 1 rev: 2.0 speed: 12 Mb/s power: 100mA chip-ID: 06cb:00c7
  class-ID: ff00 serial: <filter>
  Device-4: 1-14:5 info: Intel AX200 Bluetooth type: Bluetooth driver: btusb
  interfaces: 2 rev: 2.0 speed: 12 Mb/s power: 100mA chip-ID: 8087:0029
  class-ID: e001
  Hub-2: 2-0:1 info: Super-speed hub ports: 8 rev: 3.1 speed: 10 Gb/s
  chip-ID: 1d6b:0003 class-ID: 0900
  Hub-3: 5-0:1 info: Hi-speed hub with single TT ports: 2 rev: 2.0
  speed: 480 Mb/s chip-ID: 1d6b:0002 class-ID: 0900
  Hub-4: 6-0:1 info: Super-speed hub ports: 2 rev: 3.1 speed: 10 Gb/s
  chip-ID: 1d6b:0003 class-ID: 0900
Sensors:
  System Temperatures: cpu: 40.0 C pch: 46.0 C mobo: N/A
  Fan Speeds (RPM): N/A
Info:
  Processes: 277 Uptime: 7m wakeups: 1 Init: systemd v: 249 tool: systemctl
  Compilers: gcc: 11.1.0 Packages: pacman: 876 lib: 192 Shell: Bash v: 5.1.8
  running-in: konsole inxi: 3.3.09

Which exact laptop model do you have.

it’s a Clevo based model
here more specs
mine differ for having i7 10875H and 15,6 Samsung Amoled display and NVidia GTX 1660 Ti

display backlight control from keyboard worked well from kernel 5.11 to kernel 5.13

after today update the problem persist along with the shutdown message “Failed to unmount bla bla bla”

after the 2022-01-02 update yet not screen backlight control with Fn + F8 -F9… kernel 5.15.12

kernel 5.13 works fine…