Can someone explain this puzzle to me?

https://www.chess.com/puzzles/problem/2219562

The solution is the Knight on F5 to G3, and that's it. Why? What's the benefit here? Pawn or Knight takes and...what am I missing? This is literally the last move I'd think to make.

Hm doesn't load for me...

Hmm. Okay. It's puzzle #2219562. I don't know if that helps. Tried to post a picture but it said it didn't meet community guidelines. Here's a link to my stats page, it's the most recent one I've done: https://www.chess.com/stats/puzzles/fr33pal3tin3

The point is that it will be checkmate whatever happens. Look at all 4 lines, they are not long. Basically the point is to give a check Ng3+ to clear the diagonal and play Qh3 next after which white can't do anything.

Thank you very much for this, really helpful.

You're welcome.