There are various ways one might cheat OTB, from taking one's phone the bathroom in the middle of a tournament (some allow this!!), to getting signals from an accomplice who is seeing the game in real time. Signals could be electronic to some device on the player, or visual from an audience member in the room. It's been proposed to introduce a 15-30 min broadcast delay in tournament games as one way to prevent cheating. Some tournaments scan the players for electronic devices - not sure how foolproof this is.
Actually, it isn't! Great chess bots have very different play styles and there are people currently studying them. It's very unlikely someone will come out of nowhere so to speak (as in, not on some amazing rise as a young child) with these types of techniques. I'm nowhere near these levels of chess players but have played competitively for my county as a school-kid and still play a couple hundred games a year so have some idea.
1. The driving force behind the original accusations is that Magnus felt his opponent wasn't "exerting" himself enough, compared to other young prodigies.
2. Chess.com's case is that his results are "statistically extraordinary."
3. There is a history of cheating
4. Allegations that he admitted cheating privately (though it's not clear to whom)
1, 2, and 3 could easily be cause for suspicion; however, that's not the same as evidence. The one crucial piece absent from this article is any suggestion of how he cheated.
Without providing a means, I find this piece premature and questionable. That said, I don't know anything about chess, lot alone cheating at the master level. So maybe the "how" is common sense and not difficult?
And of course, there's also this:
> The report also addresses the relationship during the saga between Carlsen and Chess.com, which is buying Carlsen’s “Play Magnus” app for nearly $83 million.