It is a typical opening mistake which good if you know and prevent it, and good if you know and if your opponent plays it then you know how to win.
Eldin sacrificed his d-pawn, because he thought he will win back in the next move, which he did, but the pawn was poisoned and could be won by a double-attack with the queen. Next time, better to win back the pawn immediately or continue with pawn down and counterplay.
When you replay the game, please look the annotations under the board and look also the variations and side lines!
I was able to win an other knight in similar way:
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