I made an anti-cheat for vanilla minecraft once, it’s REALLY easy to tell if someone is cheating it’s just developers are grotesquely incompetent when it comes to detecting that sort of thing or (more often) just don’t give a shit. They’ll just create a naïve solution then never test it. For example: minecraft’s god awful anti-fly and anti-speedhack which is just “is the player in the air for 5 seconds” or “did the player go too fast” which is notorious for false positives and doesn’t even stop people trying to cheat, just punishes players for its own fuck-ups.
It really is as simple as creating a model of what the player should be able to do, and then nudging clients towards that expected play. Normal players will not even notice (or will be pleased when it fixs a desync) but cheaters will get ENRAGED and try to cheat harder before eventually giving up. The point of a good anticheat is not to punish players for cheating, but to make it easier and more fun to play within the rules.
It’s like piracy: We had years of systems built on punishment and all they do is create resentment and people trying to break your system, but you build a system on rehabilitation and you become one of the biggest platforms for PC gaming with people willingly downloading it.