First off, reinstalling is never suggested. If you haven’t found it already, please try to read my FAQ that Brave pinned at -Retired- PSA: User FAQ - Support & Answers
Now, you mention bookmark folder losing it’s contents. If you reinstalled, that means it erased everything you had. The only way you’d have your information is if it was synced with another device or you at least had created a Sync chain and saved the code JUST IN CASE things happened. Without syncing, there would be no backup for your bookmarks. You might have been able to do a system restore to a point prior where your bookmarks might have been saved.
Your question still remains, though no response. It’s at Youtube personal library
I had been away from Brave Community a while and so not been checking on things. I’m guessing overall yours just got overlooked by people. Plus, if I’m going to be blunt, the way you phrased things is very confusing. Anyway, I’ll try to go respond over there a bit.