I have the exact same problem. None of the fixes listed here fix the problem. I have noticed that if I reboot my system early after startup without letting my system idle, the problem does not occur. I also noticed that windows update likes to do 2 rounds of background work/checking for updates - once right after startup and another batch of work later during idle time. It's after this second batch of activity that some background task hangs or doesn't get terminated and persists until it's time to shutdown.
Update: I have also reported this on feedback hub: https://aka.ms/AAhrgj3