Current Events > Positional chess mystery

(+) Yeah! (+)

I was playing blitz online with the white pieces and I looked over the ending with the engine. I can't for the life of me figure out what is going on here.

https://gamefaqs.gamespot.com/a/user_image/4/1/5/AAP15pAAE50n.jpg

I pushed the pawn to D5 in a time scramble. This appeared to be. immediately losing. I assumed it was because the black bishop can take the pawn with check and open up an attack on my king, but that just equalized the odds. They moved their rook instead to D8, which allowed me to checkmate their king, with my D pawn and queen. But in the evaluation, if they had instead moved pawn G4 with an attack on my rook, that would have maintained the very high winning advantage you see on the left (Black 8.5).

https://gamefaqs.gamespot.com/a/user_image/4/1/6/AAP15pAAE50o.jpg

This move seemed a bit mysterious, but it at least seems reasonable. They advance a passed pawn, attack my rook, and I can check with the pawn, but the black king has one square it can use to hide, D8, which is why my opponent lost when they moved their rook there. So let's say I advance my D pawn and check the king, king moves to D8.

https://gamefaqs.gamespot.com/a/user_image/4/1/7/AAP15pAAE50p.jpg

I believe that their king is safe but for the life of me I can't figure out what the black strategy is here. This is the what if scenario where I try attacking with my queen, but their king is supposedly safe and black's win is all but guaranteed with correct moves according to the engine. Here's the thing... every move seems to lose instantly for black if I try to find a move for them. Even bishop takes with check, even taking my rook with the pawn. I've never seen the chess.com engine be completely wrong but I think I tried every legal move for black here, even the dumb ones, along with the good. They swing the engine to either forced checkmate for white or massive advantage for white. Anyone have an idea?