Cheater.

Just receved a message from Lichess that I had ranking points returned because Id been defeated by a cheater. How do they even jnow? I didnt, lol.

I think lichess mods look at games to see if there is a cheater.

Lichess probably took this game: lichess.org/oEGYbtzP/black and saw that your opponent had 0 Inaccuracies, 0 Mistakes, 0 Blunders, and 8 ACPL. This is an impossible score even for a 2200. They probably would make at least 1 inaccuracy. So, it was obvious that your opponent was a cheater.

Thank you for that!