There's a 'Sync your settings' section in Windows Settings. You can turn theme syncing off there, if that is the problem.It probably has something to do with how you can have the same background on all your account devices.
But I don't know how you'd fix it. I have mine all the same and it can take a minute for them to agree .
I have been using the same 20H2 update for some time now and have not noticed the same as you have experienced.10 pro
build 19042
I dont have anything to sync with?There's a 'Sync your settings' section in Windows Settings. You can turn theme syncing off there, if that is the problem.
So have I, however its got to be something windows orientated surely?I have been using the same 20H2 update for some time now and have not noticed the same as you have experienced.
FWIW I do have two user accounts on the system and the appropriate GUI (different) wallpaper loads AOK