Daniel Rensch and others have said that Magnus has not seen chesscom cheating algorithms or lists. It had been a rumor in the chess world for a while that Hans has cheated before
He hasn't been officially shown but that doesn't mean that someone in the know hasn't leaked it to him. He's deeply connected and respected in the chess world.
Further, even if he didn't see it people notice when GMs get bans as their accounts turn inactive (which they had in this case).
Tenoke|3 years ago
Further, even if he didn't see it people notice when GMs get bans as their accounts turn inactive (which they had in this case).