Searching logs for backlight, I find this:
$ journalctl -b -0 | grep backlight
Jan 17 12:06:34 dream kernel: amdgpu 0000:04:00.0: amdgpu: [drm] Skipping amdgpu DM backlight registration
A bit of Googling reveals that this error was (probably) added in this patch.
Some more information:
A boot with 6.1.3
A boot with 6.1.6
$ lspci -k | grep -A3 VGA
04:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Renoir (rev c2)
Subsystem: Hewlett-Packard Company Device 87a9
Kernel driver in use: amdgpu
Kernel modules: amdgpu
I'm not quite sure what to try from here.
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