A gamer in Germany bought a used Ryzen CPU and was kicked out of Valorant the moment he launched it. The processor had been linked to its previous owner's cheating, and there is no serial-number lookup that can reveal that history before you buy.
Around 59% of the anti-cheat games tracked by Are We Anti-Cheat Yet are broken on Linux/Proton or have been explicitly denied support. Yet EAC and BattlEye have Proton-compatible paths. For major games such as Apex Legends, the obstacle is often a developer's security decision rather than a technical impossibility.
