how to win in the opening


What is black's response after 20. Nexf7? Or is there just a better option for white?
computer chose 20.Ngxf7 over 20.Nexf7.

Either knight taking on f7 is winning for white , so how can either move be a "mistake" ? I dont care what the beasts say a winning move is never a "mistake" imo.

Either knight taking on f7 is winning for white , so how can either move be a "mistake" ? I dont care what the beasts say a winning move is never a "mistake" imo.
i was surprised to see that the computer analysis of my 20th move was a question mark. maybe because black has a good reply against 20.Nexf7