Iphone 13 pro “Problem”

Hi, I just bought an Iphone like a week ago, and there is someting that concern me. If you take a look on the first picture it seems like a stain in the middle on the phone, and when i clean it (with alcohol or somenthing else) the same shape of the stain appears, the crazy thing is that it doesnt affect on the function of the display, it works perfectly. But for some reason that shape doesnt dissapears, any idea?