Are you playing on Linux? I was having the exact same issue as you, playing on Steam Deck just fine until recently, and then the game wouldn't even start. After trying everything you did (aside from EA Support), I tinkered with launch options and Proton a bit and finally got it to launch. But now it runs like crap. Used to get a solid 45 FPS and now I get less than 20 FPS. What's even stranger is that Steam overlay shows my CPU is only at 20% usage and GPU is at 10% usage. I even tried changing the drive the game was installed on and it's still unplayable.