

There are basicly two ways to go with regressions: bisecting or research.
With bisecting you restore a working backup, and try to isolate the breaking change. In your case you could try updating one package at time and testing. Since these are often GPU related, start with kernel and mesa. When you find the breaking update, you can either report it on your distros issue tracker, or git bisect it further to the breaking change in the source code to increase the change of it getting fixed quick.
With research, you look into relevant bug reporting databases. These include your distros issue tracker, Valve’s issue trackers both for Steam and Proton, DXVK issue tracker, freedesktop.org and kernel issue trackers.
These are a lot of work, so most people just try random stuff. That’s why you often get suggestions to do so.
Sorry I don’t have an easy fix for you.



There is Plasma Bigscreen that’s a modification for HTPCs. For touch screen based devices, a tiling WM is available for both Gnome and Plasma, though not baked in. IMHO bigger issue for both is a poorly working touch screen keyboard. This is something that SteamOS solves quite well.