Nexus 5X graphics freeze

Nexus 5X graphics freeze

Hello,

Since a week I'm having issues with my phone. The graphics seem to freeze as soon as there is a little extra processing power needed. I first noticed it with the camera. Opening the app worked, but then it often froze. Sometimes I could get into video mode, and start recording, and then the display froze. Looking in my files afterwards, I could see that the video was shot fine.
Also in Google Maps Navigation: the spoken directions are given on the right time, but just before a spoken direction is given, the display freezes for an undetermined amount of time. Sometimes only a few seconds, sometimes minutes until it jumps to my actual location.

Since then it's gotten worse. Dragging down the notification bar can often just do seemingly nothing. But after a few seconds it shows it did register all my input, because it suddenly opens, and if I had tapped my seemingly unresponsive screen at a location of one of the quick toggles, that changes too.

Looking at photos is the same, I swipe: nothing happens, swipe a few times more, still nothing. And then suddenly it moves the amount of swipes I did.

Since input is registered fine, it seems as if the the graphics processor can't keep up with the rest of the phone anymore.

Sometimes pushing one of the volume buttons seems to help the phone to "remember" that it has to do something with the screen - and the display jumps to the screen it should already show. But other times evem pressing the volume buttons doesn't seem to help unfreeze the display.
Pushing the power button always locks the screen and turns it off immediately, even if the display is frozen. But pushing it again or using the fingerprint sensor to wake a frozen display up again, results in a backlit black screen. I hear the phone unlock sound, but the display doesn't do anything for a while.

Do you have any idea how I can solve this?

The phone has started to show these issues on the last days of the July 2018 version of Android 8.1. Upgrading to the August 2018 version did not help. I've reinstalled the Android 8.1.0 June 2018 factory image, as I was sure the phone worked fine then, but it did not help resolve these issues either.