Update 21:17: Looks like Proton developers have updated the "bleeding-edge" Beta for Proton Experimental, that works around the issue. After testing The Division 2, Watch Dogs Legion, Assassin's Creed Valhalla and Ghost Recon Breakpoint on my Steam Deck too, they all also gave the exact same problem as you'll see in the screenshot below from my Steam Deck:two weeks after Ubisoft fixed The Division 2 for Steam Deck / Linux. They only ever cause problems and solve basically nothing that Steam cannot already do directly