Hello,
The solution of this problem is:
22 ... Ne4
23 Qxb5 , Nc3
24 Qb7, Qa6
25 Qxa6, Rxa6
I tried:
24 ... Ne2+
25 Kh1, Qa1
26 Qc8+, Rxc8
27 Rxa1
At this point black and white have the same pieces remaining, so to me the solutions are equivalent.
If I am correct then some players will "fail" like me and the problem will artificially have a high ranking?
It seems that in your solution after 27...Kf8 (White threatened Ne7+) 28.b5 White's dangerous passed pawns are good compensation for the piece. In the puzzle solution the black knight is able to blockade on b5. So I think the puzzle is correct.
While it's not obvious why the position at the end of the "official line" evaluates somewhere around -2.5 and the position at the end of the "alternative line" around +2.5 (not obvious to me, that is), one strong hint IMHO is that all Stockfish lines after 27. Rxa1 have black giving up the bishop within few moves after the b5-b6 advance. I tried to save the bishop as an experiment and the outcome was even worse, typically black has to choose between giving up the rook and white pawn promoting.
Ok, thank you guys for your time and advice!
The idea Ne2+ and Qa1 to exploit White's weak back rank is cute and tempting but does not work, therefore the puzzle has a high rating of over 2500.
Next time you think there is an alternate solution, check it with an engine before reporting. I have solved (or failed to solve) hundreds of difficult puzzles on Lichess and have yet to come across one that is actually incorrect.
