Sometimes the 'dubious' sac is the best move...

So where was the dubious sac?

The title is self-contradictory. If the move is dubious, it cannot be good. If it is the best move, it cannot be dubious.

The OP prob meant move 16, which is, according to Stockfish, not a dubious move. Possibly meant the OP with ''dubious'' that it was dubious in his eyes.