I have been using my 13-inch iPad M4 for 3 days, and today when I was watching this video, the screen bulged inwards when the person in the clip pressed down in the middle. I checked my iPad and found it has the same issue. There is also a video from a channel called 'Phone Repair Guru' that shows the same problem. It seems this is a common defect of this generation of iPads, What I want to ask is whether this is normal??