As a lot of you noticed, White can win a piece here: 21. Nd3! Qxb3 22. Nc5 Qb2 23. Rab1, using a skewer to win the knight. It’s aesthetically pleasing that moves 21 and 22 see the white knight and the black queen move away and then return to their original squares. The difference is that the b3 pawn has disappeared, opening the b-file for a white rook.
Not too difficult once you’re told there’s something there, as several of you discovered, but the strong GM playing white missed it because he was thinking about strategy rather than tactics.
There’s a moral here: think about tactics all the time, in every position. Even the best players sometimes get it wrong.
This position was taken from The Secret Ingredient by Jan Markos and David Navara. You can read my review here.