I've never looked into it myself but when I was graduating someone in my graduating classes final project was a cheating detection system for chess that essentially ran your moves through a variety of different chess AI's like stockfish such and over the game built up a tally of matching moves for each system, and if you matched one too closely flagged you as cheating.
I asked the guy how he would cheat against it and his suggestion was basically finding chess engines with variable "skill" levels and varying it over the game, essentially pulling out miraculous recoveries or having a good start but then forcing your AI to try to select a win state a few turns later than optimal but using the same heuristics, so it's still practically unbeatable but drags people along a bit longer to disguise itself.
Also I don't know if this exists, but is it possible to tune an AI to a specific ELO to begin with? If so you could set it to gradually ramp up over a long time so it looks like you're steadily improving over months or years and get to the top, but I imagine that wouldn't appeal to the people already willing to cheat anyway.
I asked the guy how he would cheat against it and his suggestion was basically finding chess engines with variable "skill" levels and varying it over the game, essentially pulling out miraculous recoveries or having a good start but then forcing your AI to try to select a win state a few turns later than optimal but using the same heuristics, so it's still practically unbeatable but drags people along a bit longer to disguise itself.
Also I don't know if this exists, but is it possible to tune an AI to a specific ELO to begin with? If so you could set it to gradually ramp up over a long time so it looks like you're steadily improving over months or years and get to the top, but I imagine that wouldn't appeal to the people already willing to cheat anyway.