In my experience - nothing does that - what did you change ?
The APU 7840HS using 780GPU has kernel driver so no big surprise.
From your systeminfo all looks good
[...]
Kernel: 6.9.3-3-MANJARO
[...]
Desktop: KDE Plasma v: 6.0.5 tk: Qt v: N/A info: frameworks v: 6.2.0
wm: kwin_x11 vt: 2 dm: SDDM Distro: Manjaro base: Arch Linux
[...]
Device-1: NVIDIA AD106M [GeForce RTX 4070 Max-Q / Mobile] vendor: Lenovo
driver: nvidia v: 550.90.07
[...]
Device-2: AMD Phoenix1 vendor: Lenovo driver: amdgpu v: kernel
[...]
I recall there was a quirk with mhwd where disrcrete gpu went black if it was Nvidia.
I suggest you consult the comment number two in the recent stable announcement - issues and solutions and possibly use this comment [Stable Update] 2024-06-10 - Kernels, Systemd, NVIDIA, Mesa, Qt5 - #74 by Yochanan .