Why in 12th move for Black, engines thinks it's best to sacrifice the queen?
Idk but it's actually move 14 for back
For move 12 where white KN d5 (the fork), the engine suggests pushing with Bxd2 and sacrificing queen rather than pulling queen back.
After your Qa5 move, white plays 13. Bxb4, and the queen is trapped. So you lose the bishop and the queen, getting only one piece for them..
After your Qa5 move, white plays 13. Bxb4, and the queen is trapped. So you lose the bishop and the queen, getting only one piece for them..
I would go for the Qc6 move. Qa5 is what black played in the game.