Forum profile design weird behavior
 

My forum has 6 different designs, changed on one design the user profile via the "customize profile design" option, and saved for all.
Now all user profiles in all styles have adapted this changes.
That's a really weird and unexpected behavior. Is it a bug or working as designed?
Is there an easy way to undo the changes or do I have to edit each stylevars in each design?

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Seems to be similar like this jira entry.