Duplicated Tab Groups in Safari on all Devices

From time to time safari seems to duplicate tabgroups. Can't tell why and when. Could be caused by update or whatever. They may even be tripled, quadruple or more. Seems that I am not the only one, see also https://discussions.apple.com/thread/253095992 After they are duplicated, it seems as they would be standalone - meaning if you change something in one tab group with it does not affect the other one having the exact same name. Effect on Sequoia, and all mobile devices I have as well, always on newest OS. Has any one an idea why this occurs and how to get rid of it or deduplicate again?