You _must_ have server-side anticheat if you have any at all because client side can (eventually) be bypassed - however client side anticheat is better at catch

You _must_ have server-side anticheat if you have any at all because client side can (eventually) be bypassed - however client side anticheat is better at catching subtle but low effort/obvious cheats. Also some types of cheats such as wall hacks can only be detected client side.