By default the game will launch in a very weird and low resolution and it won't register the press of the B button, so you can't change resolution in game with Proton Experimental, 9, 8 or 7 because changing resolution required a B button press to confirm your edit in the Options menu.

To fix the resolution on the Steam Deck you can download Proton 4.11, set the game to run with Proton 4.11 and this will allow you to correctly launch the game with the B button working, go into the Options and change the display mode to either Windowed or Borderless Fullscreen, press B to back out of the Options, doing so will save your display settings and then you'll be able to properly launch the game with higher versions of Proton, like Proton 9 with both a working resolution and a working B button.