Grey bars across screen

My IPad has grey bars across the width of the screen. Don’t know if it is significant but I tried taking a screen shot but the bars did not show up. I had to takde a photo of the screen with my iPhone. The bars get a lot darker if you tilt the screen away from you and look at it at an angle. The bars don’t obscure what is on the screen and the screen seems to work ok otherwise. It does seem to be not as bright as it once was but that may be just me. I’ve looked at a number of videos about grey bars but none of them looked like the bars on the attached photo. I’ve done the whack the back thing which didn’t do anything.

Anyone have any idea what this may be due to? I don’t want to pick up a replacement lcd panel if that is not going to fix it.

Thanks