It does look suspicious...however I see the matches only had around 20 moves on average so it's not difficult to get an accuracy above 90 if you just don't make any mistakes or blunders. I would agree with Ilama_I and say that it's probably a skilled player on a different account or something.
Is this a sign of cheating?
I mean sandbagging is also not allowed so they should probably get some level of reductive action or caution regardless

100% cheating. Very rarely do i get anywhere close to 90% or 100%. You need to actually play like a computer to do that. You can beat good players by playing tricky moves that the computer doesn't like. Here is an example. I played like a 1500 according to analysis but still beat a 2600 player. And at 42% accuracy hehehe not even half of what the guy in the pic on this forum got. https://www.chess.com/game/live/90439290355

100% cheating. Very rarely do i get anywhere close to 90% or 100%. You need to actually play like a computer to do that. You can beat good players by playing tricky moves that the computer doesn't like. Here is an example. I played like a 1500 according to analysis but still beat a 2600 player. And at 42% accuracy hehehe not even half of what the guy in the pic on this forum got. https://www.chess.com/game/live/90439290355
yea sorry but that firebrander guy is not a real 2600

These must have been long games? What was the time limit? i dont think its possible to cheat in bullet. Theres no time to think let alone look up moves hehe

All of those won daily games are against low rated players who are making huge blunders. For example
You hardly need to cheat to win games like this.

100% cheating. Very rarely do i get anywhere close to 90% or 100%. You need to actually play like a computer to do that. You can beat good players by playing tricky moves that the computer doesn't like. Here is an example. I played like a 1500 according to analysis but still beat a 2600 player. And at 42% accuracy hehehe not even half of what the guy in the pic on this forum got. https://www.chess.com/game/live/90439290355
yea sorry but that firebrander guy is not a real 2600
he beats me most of the time. How is he not 2600? It's pretty hard to fake a rating like that?

100% cheating. Very rarely do i get anywhere close to 90% or 100%. You need to actually play like a computer to do that.
Can you explain instead of giving 2 and 5 word answers with zero to back it? You offer zero contribution with your statements.
That's not true.
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i dont think its possible to cheat in bullet. Theres no time
This is also not true.

Chess.com detects those programs in bullet. and the moves are done in .01 of a second. And im not a kid. Im a human. I didnt even know animals could speak? Were you trained to talk and play chess?

As suggested by other members, if you suspect unfair play, report the member.
That said, discussions about cheating, potential cheating, or cheat detection are not allowed in the general forums. If you want to discuss join the following club. https://www.chess.com/club/cheating-forum
I played against someone and their entire profile looks like this. Their rating was around 1000, their entire history consists of nothing but wins and their accuracy is basically always above 90%.
I figured it could also be a very good player who is still rising through the ranks to their actual skill level, but...