There are "pied" colors in bettas, normally called "marble" and in some cases "piedbald" although some fancies will term all of them marbles. These are white and color splotches, with white faces and the coloring goes onto fins and body both.
That however looks like what most have said, an injury or fungus or infection.
Theresa Baker
No Legs and More
Florida, USA
"Stop being a wimpy monkey,; bare some teeth, steal some food and fling poo with the alphas. "