Left Side of my iphone XR screen become unresponsive intermittently

I have noticed just now that left side on my screen becomes unresponsive suddenly. I cant go back if to previous pages because the back arrow area is unresponsive, can't type "a" or "1" due to same issue. but after several touches i can type "a" or "1" or go back tp previous window.

I cleaned the screen, reset to factory default and then restored, several reboots but status is same.

It was working fine until the evening. don't know what happened. any clue?