No amount of clientside anticheat software can stop that either though, anything running on the clientside can be faked/manipulated with enough effort

Also you could argue someone could simply plug in another device that takes a video input and can simulate a keyboard and mouse

On the server side, you could check for abnormalities in a person's stats, for example if they get >90% headshots, if they're getting a lot of kills outside a weapon's normal range, amount of time aiming at enemies through walls that they shouldn't be able to see etc etc

Then, once someone is suspicious enough, flag it up to a human moderator who can watch them and verify

Not saying there shouldn't be any clientside anticheat at all but at the point of the anticheat putting itsself in kernel space it's gone too far