[https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode Start Firefox using Troubleshoot(Safe) Mode] {web link} A small dialog should appear. Click '''Start In Troubleshoot(Safe) Mode''' (not Refresh). Is the problem still there?

Are you syncing the logins to other devices ? *https://support.mozilla.org/en-US/kb/how-do-i-choose-what-types-information-sync-firefox If that is the case then are they missing there as well? You can install the About Sync extension in Firefox 72 and newer on desktop to check what data is stored on the Sync server via the <b>about:sync</b> page provided by this extension. *About Sync https://addons.mozilla.org/firefox/addon/about-sync/ Close and restart Firefox to access the <b>about:sync</b> page added by this extension (see the about:about page for possible about pages).