Hello @Sanaki, if you set the game's launch options to PROTON_USE_WINED3D=1 %command%, does that have an effect?
It does have an effect, yes. Not quite optimal/playable though.
Without PROTON_USE_WINED3D: Black screen
With PROTON_USE_WINED3D: Renders properly, but is cropped off-center to (estimated) 4:3. Alt+tabbing or otherwise changing focus will cause it to minimize, after which it restores windowed and visually frozen, though audio indicates the game is still running. Alt+enter does not work in this state, though pressing escape does exit the game as it should
Screenshot of fullscreen startup with PROTON_USE_WINED3D:

PROTON_USE_WINED3Dx1 2021-12PROTON_USE_WINED3D=1x1 2021-12PROTON_USE_WINED3D=1 %command%x1 2021-12
Compatibility Report
System Information
I confirm:
Symptoms
Reproduction
steam-272990.log