Game Mysteriously Draws

I was playing a game with an opponent and getting into some time trouble. I started checking with my queen to find a quick mate. After a couple of games, the game suddenly draws. It didn't look like there was a three move repetition to be claimed and the game was under 40 moves. My opponent agreed that it was mysterious. Is there any explanation? Or was it a bug?

Edit: Also, when looking at the analysis, Stockfish goes from mate in 8 to a draw after move 39.

Well, within 1s I noticed the same position in the last move, -2 and -4 moves. What the fuss with 40 moves?

Three-fold repetition isn’t rocket science, is it?

Lol, the position blatantly got repeated 3 times at the end.