If your backlight is wired through Nvidia then I think you may need to use the xbacklight interface. You can do it manually by installing:
sudo apt install xbacklight
and running xbacklight ...
If that works for you then I think the problem is that mutter/gnome-shell isn't using/supporting/checking the X backlight interface. Only the kernel interfaces.
If your backlight is wired through Nvidia then I think you may need to use the xbacklight interface. You can do it manually by installing:
sudo apt install xbacklight
and running xbacklight ...
If that works for you then I think the problem is that mutter/gnome-shell isn't using/supportin g/checking the X backlight interface. Only the kernel interfaces.