This is a well known issue here in these iPad communities.
This intermittent, unresponsive touch screen issue affects a continuing, growing minority of iPad Pro users/models across all 4 years of iPad Pro models, as well as the new 2019 10.5 inch screen iPad Air 3.
Take a look at these long standing, longer posts on the subject of this intermittent, unresponsive touch screen
issue, below.
There is STILL no “official” confirmed iOS updates, solutions/fixes, from Apple, after over a year, now!
iPad Pro touch screen intermittent unresp... - Apple Community
https://discussions.apple.com/thread/250085450
iPad Pro screen unresponsive - Apple Community
https://discussions.apple.com/thread/8658399
iPad Pro 12.9” not responding to touch in... - Apple Community
https://discussions.apple.com/thread/8396370
The best you can do is to continue toalert Apple to this growing issue and hammer the Apple iPad feedback pages mutiple times on this issue.
The only way to get Apple to, DIRECTLY, listen to you is to use their feedback portion of their website.
iPad Feedback
http://www.apple.com/feedback/ipad.html
Cognizant Apple employees read ALL feedback generated from all of the various feedback pages and transfers the data to the proper and responsible Apple teams and personnel , but NO Apple employees will ever respond with any type of direct, individual replies from the feedback you post.
You can post as much multiple feedback about this issue any time.
The more users that post product feedback about any product issue, the faster Apple is made aware and starts working on a fix/solution for a future software update.
As I stated, this intermittent, unresponsive iPad Pro touch screen issue has plagued a small, but growing minority of iPad Pro usrs across all 4 years of iPad Pro models for just over a year, now!
Also, you may want to phone contact Apple, directly in Cupertino, California, and calmly talk to an Apple customer service employee about this issue via the contact link below.
https://www.apple.com/contact/
Good Luck to You!