I saw the same [drm:amdgpu_job_timedout [amdgpu]] *ERROR* ring gfx timeout when mine failed. The only useful error I see that we both have is This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem. Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, xcb.
But what am I reinstalling? I see available options, but I don’t see what’s failing that needs to be reinstalled. Unless it means all the KDE ones/Xorg, as listed in the point above on yours.