Didn't KDE just start accepting vibecode?

Try running the applications inside Gamescope. It uses a separate toplevel window that shouldn't be affected by whatever Proton is doing.

You could also try either enabling or disabling Wayland in Proton: https://wiki.archlinux.org/title/Wine#Wayland

It could also be a quirk of whatever Proton version you're using. Try GE-Proton, Proton-EM, or an older version.