Weirdly, was having this problem on an iPad Pro 2nd Gen . Read a comment here about “bending the screen” - could that be the issue. I reversed this advice and for about 10 sec I gently bent/ rebent the screen (not physically, I just applied pressure to each corner using both hands simultaneously. The iPad works flawlessly since. Your mileage may vary but the solution seems to be related to previous bending. I had tried a rubber cover to eliminate static - didn’t work. Neither did a reset or cleaning the screen.