lars666, glad you had no issue with your replacement! It is disappointing to hear that this is showing up on so many other 12.9 iPads, and as I mentioned earlier, I noticed it on all of the 12.9s in the Apple Store (as did you). I am hoping the manufacturing issue has been resolved, as the build week of mine is April 2018. I am super picky with displays, and have had mine for over a month without issue. I am in no way an engineer, but have been trying to think about what could be causing this. It is a large device, and potentially having it picked up by the edge after so long is putting pressure on the edge of the screen and starting to separate parts within the display that would start to let light leak through? I have mine in a hard plastic logi keyboard case, so maybe that will help?