Why Computer suggests that move?

Ok i had this game recently which i couldn't made a good opening and lost a piece. After that i tried for a draw and since the enemy king is in center i thought i could do it which i did with an endgame blunder by my opponent.

My question is, i couldn't really understand a computer suggestion move at move 28 for black. computer suggests for Qh5 intending Qh2 check(at least i thought that way) but i saw only i lose the bishop and king can escape with Ke1 opening way for white queen to defend checks or king can just escape with Kd2 and so on. Why do you think computer suggests Qh5 at move 28 for black despite losing the bishop?

28...Qc4 loses the Bishop after 29. Qa3+ so Im guessing the computer is being materialistic, getting at least a pawn for the piece

Losing a piece for a pawn isn't exactly "materialistic".

I'm not sure I agree with the move myself, but it's obvious that you're losing no matter what you do, so I'm pretty sure it's an attempt at prolonging checkmate by checking the king and losing your piece for a pawn for the *positional* means of gaining more tempo with perpetual check, which won't happen still.

It's not meant to be a winning move in any sense, only a losing game.