All I could think of would be some browser cache but I don't see what CSS or JS code could cause this, and you said you changed browser (but even when switching you could have used the different browsers on older xwiki versions and have some resources cached).
This is going to be hard to fix if there's no way to reproduce it. Since it was open in 2023, do you still have the issue?
I'm going to tentatively assume you haven't and close it. Please reopen if you still have the issue and try to put reproduction steps from a client XWiki instance if possible.
Thx
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