Here we have Konopak vs Illner, 2015. Black to move, and white is offering a rook. 17. … Qxc5 and now whether white calculated correctly or not he is already committed to 18. Qxg6+
And now 18. … Kh8 19. Qxh6+ Kg8
20. e4! This is the move that was likely overlooked by black, covering the f5 square. Now black has tremendous latitude to make many moves, but nothing works.
20. … Be6. The best attempt, hoping for 21. Bxe6? fxe6 22. Ng5 Qe7!
21. Ng5 Rfe8 22. Bxe6 and black resigned.