Got it. Mobing the bishop to check the king creates a peekaboo threat to the queen.
Answer
That’s because after Qxf5 black can’t recapture the queen. If they do (as was the case for my opponent) there’s simply Bxb5, which is a double check and mate.
After white takes the queen the best move for black is Bd6 according to the engine, and black is just down a queen, with white having an advantage of +5.46.
Are you sure its not +5.44 ?
Black is wasting tempo to offer a queen trade
Black is not developing any pieces
Even without the blunder it’s just a poor move
Hangs the queen or is mate in 2. If queen takes queen, black cant take back otherwise bishop b5 is checkmate as its double check with the bishop and the rook and its impossible to defend/escape from both as the escape squares are blocked by blacks rook and bishop.