A file – favicons.sqlite file contains all of the favicons (a shortcut icon for your Firefox bookmarks). So, you should keep a backup of it if you are interested in saving your bookmarks ...

To save as a new SQLite file: OR Save as new SQLite file. Select the File menu and then select Save As New SQLite File (keyboard shortcut: Ctrl+S or ⌘+S) Or Simply click Save SQLite File quick action ...