IPad screen stops responding

IPad Pro 11” 2nd gen running iPadOS 15.1. Anker tempered glass screen protector.

For the last few weeks (actually ever since iPadOS 15 - coincidence…?!) my screen has worked for an hour or two, then starts to respond sluggishly / slowly to taps / swipes, then becomes too difficult to work. I then switch off / restart and all is fine for another hour or two. Then the problem recurs. My other iPad (identical in every respect, but used for work) does not have this problem…

Any suggestions? It is a real pain…!

Cheers!