Gna gna. Found out why my Ace Combat started to crash. The culprit is dwmapi.dll, which is needed for the UE4SS mod (Cheat Engine), so I can adjust the FOV – because the devs kinda “forgot” to add a gorram FOV slider to the game that I NEED and absolutely REQUIRE.

Turns out something in there results in an Access Violation on Start with Proton Experimental (and 9). It works fine with Proton 8. I do not remember switching that but that was the solution in the end 😩

This is after I carefully tried lots of stuff like resetting savegame, disable and remove other mods, fiddle with ini files, read miles of debug logs and whatnot.