The Outlast Trials from Red Barrels has a huge new update out now that brings in a PvP invasion mode, and there's also now anti-cheat added into the game.

With the update they’re also now using Easy Anti-Cheat, which has been disclosed on the Steam page as of today. Anti-cheat is rather problematic when it comes to Linux / SteamOS + Steam Deck, but in this case they do have it enabled for Linux platforms to be able to play. We were shared this message from a support ticket the developer replied to:

I’ve personally tested it just to be sure and it worked fine with a game being invaded on Desktop Linux (Proton 9). Nice to see, since it’s a Steam Deck Verified game. Our dedicated anti-cheat page has now been updated to note this.