Issue started to surface after installing iOS 12.2, I am using iPad Pro 11 by the way... it’s so annoying especially when you are in the middle of intense gaming and the touchscreen stop working, and you have to lock and unlock to get it to work again....
I share your pain!
P.S. My impression that this problem's connection to updates is accidental. iPad starts to act like that at some point on hardware side no matter if you update it or not unfortunately Something breaks inside due to bad manufacturing.