It's possible that the opponent didn't cheat in your games but cheated in the same pool in other games. However, they may have cheated against you.
https://support.chess.com/article/648-what-do-i-need-to-know-about-fair-play-on-chess-com
Discussion related to cheating, cheat detection and the likes is not allowed in the forum. If you will like to discuss about cheating, you can join https://www.chess.com/club/cheating-forum
I was recently notified that an opponent who defeated me had his or her account closed for a Fair Play violation and some rating points were refunded to me. What is perplexing is that, while the opponent played really well against me, I'm quite sure he or she was not cheating in our game. I managed to get a winning position in a double-rook and pawn endgame, which should never happen if the opponent was using an engine, but unfortunately I misplayed it and squandered the win (and eventually even lost when I absentmindedly blundered in what I thought was a threefold repetition). It was sad but educational.
I would hate to see anyone banned unfairly. I realize the site has all sorts of involved ways of detecting cheating, so I suppose this was probably not a false positive. I am confused as to what happened, though. Is the most likely explanation that this opponent was found to have cheated in some other game?