I'm running Endeavour OS (KDE Plasma) and ran into a weird issue with my graphics. It's like windows sometimes flicker and flight with each other, some fullscreen videos won't play and just lock to a gray screen instead (e.g. in Steam, though YouTube is oddly fine), and most 3D games are super choppy and unplayable.
I'm not asking how to fix this, I just want to know how I start troubleshooting! I haven't done anything special with my system, and I think the issue started after a normal pacman update. My GPU is a GeForce GTX 1060.
Any suggestions to get started? I don't even know if the issue is Nvidia drivers, X, window manager, KDE, etc.
EDIT: The problem was Wayland. Fixed by logging in with X11 instead!