The march of the h-pawn is also threatened, so Black resigned.

A standard, though very strong sacrifice.

After 20...Qxd4, White wins by 21.Qxd4! Bxd4 22.Bxe6 Rxf7 23.Bxf7+ Kxf7 24.Rc7 Bf6 25.Bc3 Re8 26.Bxf6 Kxf6 27.Rxb7±.

Bad is 21...Qxd4 22.Qxd4 Bxd4 23.Rxe7+–.
Black had counted on the pin, but...

A brilliant queen sacrifice.

For the queen, White has rook, bishop and two pawns, but Black’s biggest problem is the weakness of g7. The attack is unstoppable.

Black resigned.

White blocks the f-pawn from moving.

But not 25.gxh3 Qc5+ 26.Kh1 Qc6+ 27.Kg1 Qc5+=.