You don’t necessarily need to detect the cheat itself, you can look at things like players having suddenly higher kill rates and put them into a queue for observation by either more advanced (more expensive) automation to look for cheating or eventually involve a human in the loop.

That’s true, if the player suddenly has higher kill rates. However, that doesn’t work if they’ve been using the cheat from the start on that account. A sufficiently advanced AI powered aim bot would also be nearly indistinguishable from a professional player. Kind of similar to how Google created the CAPTCHA that uses mouse movement … but had to go back to (at least in some cases) the additional old school captcha.