Ok - want to hear something weird that makes no sense? Saw on a reddit thread yesterday where someone updated to iOS 12.2 and the touch issues went away with their 11" Pro + glass protector. I did the same last night and was shocked that it's working much better for me now as well.
I tested by resting it on my bed atop my comforter which should make it start "glitching" unless I have a finger on the metal frame on the side of the iPad. Scrolled, tapped, gestures, no issues.
Propped it up on the bathroom counter (usually triggers the same problem) - same thing, seems to work fine. I'm not sure how an OS update could've fixed it, I assumed it was wonkiness between the glass thickness and maybe all the extra magnets on the new Pros. Glad it's working much better now though
Reddit thread:
https://old.reddit.com/r/ipad/comments/b5fi92/ios_122_seems_to_have_improved_the_touch/