Why are these 2 moves a "mistake" and a "blunder"?

I just analyzed my 1000000th game with Stockfish. I usually try to understand my errors/blunders through it, but this time I can't see why my moves were bad.

I'm Black.

Move 22 apparently is an error. Why?

Move ...28 is a blunder. This one I don't really understand. My knight is protected, and I'm threatening checkmate with my rook.

Any idea? Thanks

And sorry by the way, I realized I posted this in the wrong sub

28...Rf1 is mate

Aha, now I understood that error, thanks!

About the blunder, I meant ...27, my bad

Again...I wouldn't get up in what the engine says.  "Blunder" in this sense just means that you didn't play the strongest move, but black is still certainly winning with the extra pawns.

Alright

Thanks once again