Hi Amy JE: When I first posted this awhile ago, someone responded with this and it worked:
Disabling the option "Automatically launch app at startup" in the Xbox app settings should disable the Game Pass advertising.
1-Click on Start, search for the Xbox app, and click on that
2-Click the Profile/Sign-in menu item at the top-left of the screen
3-Then click on Settings
4-Click on General in the left panel
5-Then uncheck the option "Automatically launch app at startup" under Startup settings
6-When finished, close the Xbox app and should not see this advertising again
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