To be honest, I was surprised and I disagreed, as there were several positions in which both players could make a lot of mistakes and the final result in this cases should not have been a draw. The level of the players is not important, but the moves, made before the flag has fallen, are the first criterion. He had recorded about 16 moves and then 16 moves later he had checkmated his opponent. The game was not even close to the time limit. His opponent claimed that the game was invalid.
Checkmate finishes a game.
This means the result stands. But I would like to make several observations. First of all, the opponent should, during the game, go to the arbiter and should demand that the arbiter require the player to record the moves. Secondly, the arbiter also did not do his job. I have a question that perhaps you can answer for me.