My iphone 6 touch screen recently started not responding intermittently

Versions:

Software version 12.5.2

Model Name: iphone 6

Model Number: MQ3D2FS/A

I have gone through the steps on the page "If the screen isn’t working on your iPhone or iPad" - The problem still keeps recurring

get.support.apple.com care says the phone is out of warranty, so I'm on my own

Searching this forum, it seems to be a common problem. Does anyone know what the solution is?