The Estimated Elo in game review is not designed for cheat detection and can be really high sometimes. Using it as a guide to detect cheating is erroneous and misleading. If you suspect someone of cheating, report them and let the Fair Play team look into the account.
https://support.chess.com/article/209-how-do-i-report-someone
https://support.chess.com/article/648-what-do-i-need-to-know-about-fair-play-on-chess-com
https://www.chess.com/article/view/online-chess-cheating
Discussion of cheating, cheating detection and the likes are not allowed in the public forums. You can join the Cheating Forum Club and recreate this post there to see what others think. https://www.chess.com/club/cheating-forum
There are many ways on how to cheat at chess specially online but how can we tell if someone is having an assistance from other person or artificial being stronger than him the whole game or arbitrarily? I am alway curious and yet puzzled on how to know it and accidentally after running chess game reviews a bunch of times, I am accidentally struck by the fact that there might be a solution to this problem. One of the thing I notice about this feature is it estimates a players strength based on their moves compared to a chess engine and this may provide a benefit of ditching a lot of uncertainties that will blind us on our endeavors to learn the truth to a garbage can of anxiety superficially. The bright surface will light upon us even though it is cold in our adventure to catch a prey that rob us our happiness on playing this game. To make it sure that he will not slip from your keen eyes is to make this following step.
Step 1: Click the Game Review after the game
Step 2: Look at the Estimated Elo of players at the end of it
Step 3: Subtract 500 points from your Opponent Estimated Elo.
Step 4: Compare it to your Opponent's Elo
If the (Opponent Estimated Elo - 500) is greater than their current Elo, they might be cheating.
How did I find the number 500? It is because Chess Elo is using an Elo rating system that if a player whose rating is 400 below than his opponent is going to win only once in every 10 games between them. And a rating of 500 difference will result to a win of only once in every 20 games and it will reject the null hypothesis that he is not cheating with a p-vlue of 5 percent. Therefore, he is cheating.