That pawn is going to promote, or white can move the rook in the way, and lose his queen... M6. Look at the 📌 on the white queen.
Stockfish: 43.Qxd3 fxe1=Q+ 44.Kf4 exd3 45.g5 Rf2+ 46.Kg3 Qe3+ 47.Kh4 Qe4+ 48.Kg3 Rg2#
cool