@waspennator Thank you for the report! I am able to repro this, and we are looking into it. :)
Still broken on latest Experimental build and still marked as playable on deck, here's a pic to show the specific errors, dunno why this worked on older Proton versions.
Regression has been fixed as of latest proton Experimental update.
proton experimentalx1 2024-08
Compatibility Report
System Information
I confirm:
Symptoms
Game seemed to work fine with what I'm assuming the version of proton it was tested with (6.3-8), but it seems like recent versions of Proton crash with a vertex shader error. Problematic since this game is marked currently as playable on deck using proton.
steam-274290.log
Reproduction
Start the game.