Why did this happen?

#8 No I didn't read the TOS.

Well if you don't understand that turning on the engine on the current position in a rated game constitutes cheating, then we'll have to take action. We can't have legit players facing cheaters, you see.

Last chance for you to convince us that you understand the rules.

Look I'll try to make you understand my situation.
I play the Sicilian Najdorf otb, and right now I am playing in a tournament.
The line my opponent played was the Sozin, which is an important line and also likely to occur in said tournament.
I didn't know any theory, and since it can occur in a real tourney game, I needed to be prepared. Of course whenever I prepare for an opening, I usually switch on the engine and analyze it at some depth, usually to 0.00s.
Now generally I use ChessBase for this, but this time I thought it would be more convenient to use lichess. So I clicked open with new tab, opened analysis board, put on the analysis board. Then I put this position and switched on engine, and this happened.

I don't know what to tell you honestly. This is how one prepares for a game! I would do the same on ChessBase anyways. Are you saying that because a correspondence game is on, I can't do my normal preparations? Imagine if someone plays this otb against me, anyways I would prepare it with an engine, as anyone at my level does. But then the correspondence game still remains going on, and I can use my otb preparations.

You cheated on your opponent. Either you play or you prepare.

But both the correspondence game and the otb tourney are happening at the same time! I was doing my normal preparation. I would never cheat in my life, and have never cheated. I would rather quit!

Firstly, like every Najdorf player knows, on move 7 in this variation b5 should be played, not sure why you played Nbd7 - seems very odd with the knight and bishop eyeing e6. Secondly, in the position after f5, what was so hard in the position that you felt like wanting the engine's help. You're an IM and a very strong player, so do you really need to prepare while playing a game? just play Be7, play the game, and analyse afterwards right?

So playing unrated (with a friend or a coach) with engine assistance and/or opening database wouldn't get me banned? Can we use the opening database on a rated correspondence game? The limit is a little bit imprecise to me :P

It's a correspondence game, it goes on forever. If it was a short game that would be no problem of course. And yes, I don't need to prepare during a game, but here I am trying to prepare before an otb game.

Btw, I thought Nbd7 is supposed to exploit Bb3, which is why 0-0 is a better move. I am pretty sure it is theory.

If someone is playing dozens of correspondence games and have an OTB tournament to prepare, he shouldn't be handicapped. And I believe that on Lichess there are more players trying to prepare than cheaters.

Edit: However I don't have an alternative "rule" to suggest, just my opinion :)

@Koustav123456 let me explain how this works: you can use the board to move the pieces around in any way you want so you can analyse it with your own eyes. But you can absolutely not have any engine on once the game has started. You can study positions with the engine prior to starting a game but once the game is in progress using an engine at any number of moves is 100 percent cheating. According to what you have said you have already broke this rule several times.