So, background autostart was disabled for all my apps. I am not sure when this happened. RAM was so set to clear 5min after locking.
Makes me think I implemented some battery/power saver setting at some point causing this.
My Mix 4 also has that, but smaller. It's annoying because when it's over the keyboard you cannot type. It's not a problem that needs fixing for me, but a minor annoyance. I see your problem is bigger haha