Another reason why a lot of One Piece fans might ask "What is Stussy's Devil Fruit?" is because she isn't a normal person since she has been revealed to be the MADS' first-ever successful clone ...

Cloning is a key sci-fi trope in One Piece, enhancing characters like Pacifistas and Seraphim with new abilities and genetic components. Germa 66's army of clone soldiers, Pacifista, S-Bear ...