Firefox keeps backup in the bookmarkbackups folder, so you should be able to restore the bookmark to the state from before the import.

• https://support.mozilla.org/en-US/kb/restore-bookmarks-from-backup-or-move-them

The name of automatically created JSON bookmarks backups in the bookmarkbackups folder includes a total item count (folders and separators included) and an hash value to prevent saving the same backup more than once. You also see this count in the Library Restore menu drop-down list.

• bookmarks-YYYY-MM-DD_<item count>_<hash>.jsonlz4.

I tried to do a restore, but only found options from three or four years ago.

I think Firefox usually keeps up to 15 files, so that should go back at least two weeks, and possibly further if you don't add bookmarks every day. But I don't know why you would see such old files.

Could you type or paste about:profiles in the address bar and press Return to load it. Usually the first entry is the "default" profile that hasn't been used (since Firefox 67, new installations use the "default-release" profile). But for investigation purposes:

Each profile on the page has a Root Directory row with an Open Folder or Show in Finder button. Click that button, then double-click into the bookmarkbackups folder. Do you see any files here with 2024-11 in the file name?

If you find files you want to investigate, I have a tool to convert the compressed file into an HTML file for easier reading. https://www.jeffersonscher.com/ffu/bookbackreader.html