If a game installs a client side anti-cheat, it must say so on the Steam Store.
It's going to be easier to spot which games make use of anti-cheat services on Steam soon, thanks to new labels added to Steam Store game pages.
In an update shared earlier today, Valve detailed that developers can now share anti-cheat information via their game listings on Steam, which once filled out will display clearly to users.
This change has come about due to developers "looking for the right way to share anti-cheat information about their game with players" along with players requesting "more transparency around the anti-cheat services used in games".
Thankfully this change to share such information is now a requirement for titles that make use of client-side kernel mode anti-cheat tools. Valve don't require disclosure if the anti-cheat technology being used is not kernel based, but encourage developers to let players know all the same.
Just last month Rockstar added anti-cheat software into GTA V, essentially making GTA Online unplayable on Steam Deck. Changes like this should now be much clearer, visible, and obvious on the Steam Store.