Fractalgender is, like a fractal, an infinitely intricate gender. Fractalgender people believe that their gender is infinitely complex in nature, but their identity repeats itself in multiple facets of their being.
Fractalgender can also refer to anyone whose gender feels shattered into a billion different pieces.
Fractalgender people can use any pronoun, depending on what part of them feels most self-similar. You can be Fractalmale, Fractalfemale, Fractalnonbinary, or even Fractalfractalgender, if your gender feels so broken up that you need the term "Fractalgender" to describe how you're Fractalgender, which is consistent with what a fractal is.
The flag is a rainbow Mandelbrot Set, a very famous fractal. The rainbows represent the variation in gender, where the fractal itself represents the fractal nature of that gender rainbow.