Lesson
White to move. Main line: 22. Qf6+ Nxf6 23. Be7#
22.Qf6+! forces the knight from g8 to capture. Black has no time to use the queen and rooks already collected on the other side of the board.
The capture clears e7 for 23.Be7#. The bishop checks on the diagonal while the knight on g7 and Black’s own pieces remove every flight square.
The sacrifice is sound because it is forcing from start to finish: check, forced capture, checkmate. Material never gets another move.