I don’t want to be pessimistic, but I consider that in this scenario (as a Battlefield 2042 player) there are only three possible options:
The company kindly activates Proton/Wine support, but they don’t do it because they love their users, they do it because they realized that specifically the Steam Deck has a certain market share that they are losing.
Valve makes an agreement with those companies and with the anticheats and allows us gamers to play from Linux as if it was Windows but not bypassing the anticheat, but implementing some kind of anticheat also for Wine/Proton.
The one I consider most likely, we’re screwed and we’ll have to wait for some hacker (or experienced users) to figure out how the hell to make the anticheat think we’re in Windows when we’re really in Wine. It seems to me that this happens with some Wine prefixes that I have no idea make it possible to play LOL on Linux.