I've been deleting my saved passwords in Firefox, after migrating to a standalone password manager. It's been anything but easy (deletions are not synced, and bulk deletion process is inconvenient to say the least). What worries me is that my "deleted" passwords kept coming back as soon as I enabled Sync, until I realised I had duplicate devices in my Mozilla account control panel. I still have, though, some other connected services (Add-ons, Mozilla Support, Mozilla Monitor...). Is what I've done enough to ensure they're gone? Where exactly are synced passwords stored, and how can I be sure that they aren't lying around in a Mozilla server, awaiting a future data breach? I don't have the time and energy to change 200+ passwords.