One, and only one of my sprites despite all of the code being the same, appears to be lighting up when I move my mouse near it. I haven’t done anything to the game object’s sprite, or anything at all related to the look of it. The sprite is a solid white semi-circle.
Actually, not particularly. Do you use any custom rendering pipeline and/or shaders? What do you mean by lighting up? Can you post a screenshot or a video?