Subfolders displayed with the folder as "Folder\Subfolder" when created outside of LRC

It looks normal now with Photo 2022 and inside the subfolders. This happens to one of my community member, so I cannot unfortunately  make more tests.  

Agreed - I would go further, it's IMO unwise to use any such characters for folders or for file names and the like anyway, not just so far as Lightroom is concerned. They may be apparently fine but then still cause problems when you, or other people, try to use them in another context.

I would go further still and advise against any remotely special character for anything that may be involved in later processing of any kind. Outright text content is OK (such as a caption or a notes field, or the words inside a text document - all applications know to surround that sort of thing with quote-marks - to only handle it with thick metaphorical gloves).

To give an idea: I had an task some time ago, to use a utility to archive a lot of emails as separate files on disk (in "msg" format). That was fine except that one correspondent liked to punctuate the subject lines of his emails with semi-colons. Seems trivial, and the email system had no problem with this. But now this email subject had to be used in the new filename, thus every email that included such semicolon(s) needed manual editing within the email system console, to replace those with the commas they always should have been. Otherwise each one would generate a separate error and separately refuse to archive. That also included every reply or forward to these same emails, if it had quoted the problematic subject line. So HIS eccentric and innocent whim, cost ME many hours of completely needless and increasingly testy toil!

Thanks. It did the trick.