This issue was first recognized for me about 2-3 firefox versions ago

It’s weird, first time something like this happened to me, I’m on Fedora ( FF v124.0.1 ) and I don’t think it has anything to do with how you close windows, I was organizing my bookmarks I checked Lemmy for a second, went back at it again, to see that my work gone… I didn’t touch anything…

The only thing that I think caused it is FF Sync, because it keeps running in the background… But you don’t use it, which is why I said it’s weird…

One instance has about 50~ bookmarks with 3 folders no subfolders, one instance has about 500 with many subfolders… I assume only recently added bookmarks have disappeared, but I have no way to verify and my memory wasn’t perfect

My bookmarks were there for more than a year, they didn’t vanish until I started moving them around, so I guess there’s a bug that affects large folders

Tab Stash Bookmarks aren’t affected…

I use privacy badger, privacy possum, adguard with most filters enabled, decentraleyes, and user agent switcher.

Unrelated but why all these ? you can reap better results ( reduced attack surface, better fingerprinting protection ) with different extensions,

Ublock and enable : Adguard URL tracking protection

Firefox Containers : Isolates websites/activies from each other

Cookies ( Privacy Badger ) : FF has Total Cookie Protection since v86, you just need to set the protection level to Strict mode

Fingerprinting ( Privacy Possum, UAS ), redundant with RF ( resist fingerprinting ) feature, go to about config, and search for privacy.resist fingerprinting > enable it

decentraleyes : redundant with Total Cookie Protection

The only two you need really, is Unlock and Canvas Blocker ( if you’re not going to use Arkenfox ), FF containers

Edit : sorry, three…lol