@MickiTee -
I wasn't too bothered about bookmarks, mine are pretty static and I had them covered elsewhere, it was the potential loss of customisations and extensions that really bothered me.
After I restoring
%appdata%\Mozilla\Firefox from my backup drive the only thing I lost (apart from the recently added bookmarks) were my 'permanently' pinned tabs, I have managed to get them back, but I'm not sure how or why.
BR