cheat detected?!

I was playing this casual game with my (real life) friend

It says "cheat detected" and gave me the victory.

The game just started, he didn't play any masterful combination or anything.

He said he was shuffling tabs on his phone.

Could this trigger a cheat detection?

Either way this was clearly a bug!

If you checked analysis, your friend has 0 errors.

This warning is hard to trigger, normally it only happens when you have an analysis board with the engine enabled on another tab (possibly with the same position)

@FuryPhoenix sure, but it's only 8 moves. And if you look at the actual moves they're very obvious. Things like recaptures and direct attacks.

@Solal35 as for opening the analysis board in a different tab f you look at the move times, he played very fast. It's incredibly unlikely that he would have been able to do that. Not to mention that I know him personally and we've played lots of games where he blunders all the time. The probability of him cheating is basically zero.

Much more likely that this is a lichess bug. Can someone not actually check how this was triggered in this instance?

I'm really not looking to debate whether he was cheating. I know he wasn't. Just reporting a bug.

They are literally textbook ruy lopez - exchange variation moves. So I guess it's not (just) the moves - perhaps each move was looked up on the same device using an engine and it's this that caused the cheat accusation.

The one who is playing quickly in the opening is Black.

White, for unknown reasons, takes 8s, 10s, 8s, etc for extremely normal moves, which he must know. He says he was "shuffling tabs". Yeah. What did he do that for, I wonder..

White had an analysis board open in a different tab, with the engine on, and copied over the moves. Or checked the Database. Or played the same moves against an Engine on lichess.

This autoflag happens thousands of times a day, and it's never "a bug". Your friend was cheating. In the most stupid way possible.

If you want to actually make sure that he isn't cheating, tell him to make an account, rather than playing as Anon.
This type of behavior will get him marked within a few days. It won't be a bug then, either..

Anonymous people can play against the members?

I think the member can create a game against a friend, and send anyone the link.
"The first person to come to this URL will play with you."

@IsaVulpes So your theory was that my friend used an engine for moves such as 1.e4 and 2.Nf3? With respect, that strikes me as absurd. The only move which was non-obvious (at my level and his) was 9.Qb3 for which he took significantly more time (20 seconds vs <=10s for the prior moves), consistent with a non-cheater.

Everyone in this thread is assuming that he cheated. I was hoping a developer could double check if it's a bug . Likely, a set of conditions that is usually met by cheaters was hit by my friend (e.g. 9 straight moves without error, fairly consistent move time, shuffling between tabs, player without proven track record -- in this case anonymous). I suspect a developer might defend this by saying that this was a false positive, and that the rate of false positives is low. But perhaps the algorithm could be improved upon by this example of a known non-cheater triggering this particular false positive.

But since everyone in this thread is merely interested in making assumptions, it seems my issue will not be taken seriously.

I was not asking for unfounded speculation, which is all that I got in these replies. I'm not interested in debating whether my friend cheated; I know he did not.

It's really not that big a deal, I just thought I'd be diligent and report the issue I hit.

I've cheated before lol.