This appears—or is supposed to appear—identical to the rainbow flag this is a remix of. But there is a difference between the two.
The original contains six rectangles, each of a different color, representing the six straps of the flag.
This remix contains just one rectangle with a rainbow of the same six colors as appear on the rainbow flag, created using the SVG linearGradient element.
The advantage of this remix is that the linearGradient can be used to fill any SVG object without the need to stretch or squeeze the image of the flag to the right size to fit the object. Filling the object with the gradient forces the SVG host (such as the browser) to fit the object with the right size rainbow image automatically.
The disadvantage is that apparently certain SVG interpreters get rather confused by the linearGradient element. I’m talking about Serif DrawPlus X8, which does not preserve the sharp edges between the stripes of the flag here.