Is anti-cheating system working?

And if it is working, how does it work? Is it necessary to report the player you think is cheating or it is automatic?
In one instance I did not report (and wasn't suspicious at all of the player) and 1 hour later I received back my points.
Then, I played a guy who is clearly a cheater (I look through his games) and reported him. Nothing happened. I look through his profile and he keeps doing it...

Am I suposed to provide the site with a detailed report explaining why I think he is cheating? Or there's an A.I that can detect it instantly?

I know those are common questions, but I did not find the answers anywhere. Thanks.

@ballarat Lichess anti-cheat detection is definitely working. As to how it works, they don't say their exact method because they don't want to make it easier for cheaters to avoid cheat detection as said here lichess.org/faq#marks. It isn't 100% necessary to report the cheater because their cheat detection is automated or it at least seems like it; however, reporting also works. If I had to guess how their cheat detection works; it probably uses a lot of algorithms and comparisons between the players move and the engines. They could also check your level of play compared to recent past play. If you suddenly go from making 8 blunders during a game to playing a perfect game, they're likely cheating. They definitely use other methods to find cheaters as well. It could take a while for a user to be detected for cheating, especially if it's being reviewed by a team of people.

Anti trapaça precisa ser denunciado, entra no perfil do jogador e faz a denuncia e cola ao menos 2 links de partidas que serão analisados

There is an easy way to spot cheetos.

youtu.be/XSMZhCCEFuA

Regarding the player that you did get points back, Lichess will return points to everyone who played against the cheater recently, subject to certain other conditions. So if you play against player X, who is a cheater, and then I play against player X and report them, theoretically we can both get points back even though you did not do the report.

Reports do take time to process though, depending on things behind the scenes at Lichess. Lichess has roughly 2-3x as many games being played right now as it used to at the start of the year, so some things like this may be behind, and they may be prioritizing other cases (e.g. cheaters in active tournaments tend to get caught/punished very quickly). It's also possible that person who you played did not actually use an engine.

The guy was actually a cheater, about 2 hours ago I received a message saying "someone you reported was banned". I did not get any points back though, but thats ok :) This one was pretty obvious cheater, not very smart.

@ballarat - First of all, this is not a chess discussion. You should have asked your question in Lichess feedback, where this matter has been discussed thoroughly already.
The refund of rating points only makes sense when their loss is very recent. Usually after 3 or 4 games you are back on the level you deserve.
I think if you suspect someone it is good to report them. I have similar experience like you, sometimes tehre is no response, sometimes a little thank you when there was a ban indeed. I trust that the Lichess algorithm are better than my insight whether or whether not somebody plays fair.

@Far_Aiir

You wrote:
"If you suddenly go from making 8 blunders during a game to playing a perfect game"

That's not a good indication. I have super sharp long games which ended in tons of blunders and mistakes, and on the other hand perfect games with 0 blunders 0 mistakes and 0 inaccuracies with low ACL.
Does it mean I'm cheating? no, cause I don't.

@orior I think you misunderstand what I meant. I mean if the majority of your games have around 8 or so blunders, so not just one bad game. For example, if my rating was around 1000 for the past x amount of months and I have a couple of blunders, mistakes, and inaccuracies every single game I play and suddenly jump from 1000 to 2000+ and win the majority of games (which would be against stronger opponents). It would look like I was cheating, right? Another way people could find out if you were cheating is by making moves that a normal human wouldn't play. I'm not saying it's impossible to play at a higher level once in a while either.

@Far_Aiir
Ok, that makes more sense. Still, looks like a pretty complicated algorithm to code taking account all possibilities without accusing legit players or passing by cheaters. In any case - Lichess is doing a pretty good job in keeping cheaters out of the site.