The issue is that there's often a lag between opening Firefox and the extension loading, so for a few moments the private folder (and sometimes its content) is visible in Firefox's bookmarks sidebar, rendering the extension practically useless.

bookmarks are not deleted when I turn off the add-on

Doesn't work on Firefox Developer 91.0b8. I checked the github page to submit an issue, but it seems like the project is dead and the developer is no longer responding to issues... I don't think this should have the "Recommended" tag as it's no longer being maintained.

changed password without user confirmation, lost data. backup bookmarks or they will be lost. doesnt actually work after a while. 5star reviewers lie or gave 5 stars too early.

turn off the sync to use it

After a Firefox update, my password doesn't work anymore. It seems this happened to other people too. The addon hasn't been updated in two years so I don't recommend using it. If you do use it you should regulary export your private bookmarks as plain text file

this extention won't let me add any bookmarks

RSN