Can't change screen brightness

another clue could be that from the Oct update EOS seems to have made a change, and the intel nouveau package was removed to allow booting computers with nvidia. I think you are on the path of solving this.

@joekamprad could that create a problem for his intel card driver? Intel UHD Graphics 620

We removed the xf86-video-nouveau package and are using the mod-setting driver in the Linux kernel instead