Black won because it appears it is not a normal game, but some sort of variant. In a normal game one wins by the opponent running out of time, or by checkmate. This game states black won by putting the king in check 3 times.
Weird loses/wins
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How did this person win? https://www.chess.com/game/live/129709154831
Also, what are some games you cant tell why you won or lost? I am terrible at chess, but some other people might be able to help