Bright spot above Home button on iPad Pro 10

I faced a marriage on my ipad pro 10.5 as a bright spot on the screen, which is noticeable only on a light background and is highlighted by the fact that it is a bit lighter than the rest of the image on the screen. I gave my tablet in service center and in a couple of days I was given a new one. And now, six months later, the same spot appeared again in the same place at the replaced device. Spot it on the screen above the Home button, 3-4 centimeters from it. Does this problem affect all devices of this line? When I was replaced with a new tablet, then some time this spot was not, appeared later during operation. The tablet is always used in a case and with protective glass. What to do in this situation? To reconcile or again to take the tablet to the service center for replacement? Why does this stain appear at all? And why does it appear in the same place? Is there any chance that it will become brighter or will similar spots appear on the screen?