illegal move by the opponent
Was it en passant?
https://support.chess.com/en/articles/8557558-what-is-en-passant-it-s-not-an-illegal-pawn-move
Was it en passant?
https://support.chess.com/en/articles/8557558-what-is-en-passant-it-s-not-an-illegal-pawn-move