Whats wrong with the engine?

Ive just played this match, i won by check mate by moving the rock to g4 but cant understand why the engine said that the best move is to move rock to f3 even when there is a mate in just one move -.-

There is no mate in one in the posted position. If you are thinking about moving Black's Rook to any square on the g-file, other than g1 of course, to immediately checkmate White's King, that does not work because White can block the Bishop's check with f3. For example, 19... Rg4+ 20. f3 (only legal move) Bxf3+ 21. Rg2 (only legal move) Rxg2 (White is hopelessly lost).

The engine's recommendation of 19... Rxf2+ is also good, since it captures a pawn while revealing a discovered check on White's King with the capture of the Rook on d2 to follow (19... Rxf2+ 20. Kg1 Rxd2).

Thank for your answer you are rigth, I spend 10 mins whatching at it and didnt see that pawn,

That happened to me recently.

I looked at a position and said to myself: "Wouldn't moving that rook be checkmate?" But then I realized that the pawn could block lol.