Cheating in Chess
They were likely using a problem to play strong moves, so when the admins found out they likely adjusted your rating by recalculating it as if those games never happened.
If you look through the games you lost where your opponent's account has been closed, they may have committed a fair play violation. I happen to notice someone had been registered for over ten years and was recently closed because of this. Why TF they do doesn't make sense to me. It doesn't earn you more money or grow your todger or cure baldness. It just bumps up a number that has utterly no significance.
https://support.chess.com/article/648-what-do-i-need-to-know-about-fair-play-on-chess-com
Take a look through that and it will explain most things. Discussions of cheating, potential cheating, and cheat detection aren't allowed in the general forums.
If you would like to have such a discussion, join the following club.: https://www.chess.com/club/cheating-forum