Weird puzzle

I was playing puzzle rush and this puzzle came up. I played Nd7 and Nxe5, but it wasn't correct? My idea was to take the more active rook. Can someone explain why to play Nxf8? This is the link of the game the puzzle is from

sorry, link: lichess.org/IMbX6dEs/white#44

24. Nxf8 is correct because white can then force the win of the black knight.

24. ... Nxf8 25. Rc8 g6 26. Rbb8
24. ... Kxf8 25. Rc7 Kg8 (only move that prevents checkmate) 26. Rb8+ Nf8 27. Rcc8

Here's a link to the puzzle: lichess.org/training/Ablv4

It feels like it ends prematurely.

But after Nf8 both Rb8 and Rc8 are equally good.

And after Kxf8 both Rc7 and Rb7 are equally good.

So there's no unique solution that would allow the puzzle to continue.