Does My Screen Protector Have the Rainbow Effect?

That is definitely the protector not sticking to that spot. It moves because the area just keeps lifting. You can ask the manufacturer for a replacement if they have that kind of warranty (the protector, not the phone). But yeah, nothing to be concerned about other than the nuisance of having that always on your screen. If it gets too bad, though (actually fully lifting) you might also notice reduced touch sensitivity on that area due to the added air layer between the screen and the protector, but that would mean that, somehow the protector has really lifted up and you're better off replacing it anyway.