Sometimes the phone stops responding to tap touches, while swipe still works

This happened for me a few times the last few days, but I don't know any recipe to reproduce it.

What happens is that as I am about to unlock the phone, it responds to the swipe so the numeric keys are shown, but then it does not respond when I try to enter the pin. Nothing happens, seems like it does not register those touches, It still responds to swipes though. The problem goes away if I start over by pressing the power key twice.

Video:

output

Suggestions for how to troubleshoot this? If/when it happens again, I could probably ssh into it over wifi while it is in that funny state.