Same here in our CI system that authenticates via fastlane:
An error occurred saving your changes to the Apple database.	This problem may be a transient issue on the Apple side.	If the problem persists for more than an hour, please contact your iTunes representative. (1129)
XCode Version 12.0.1 (12A7300)
christian48
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For me working again, too.
Xcode 12.1 (12A7403)
macOS Catalina 10.15.7