I see. Doing some googling, it seems like it's this godot bug:
https://github.com/godotengine/godot/pull/74566
I haven't seen this so maybe it's Linux-specific or only affects certain graphics cards. There's no workaround, so unfortunately I think fixing it would require someone smarter than me fixing the game engine, or porting this fix over to 3.5.x. Thanks for the report, I wish I could do more to help!