All my tabs are disappearing permanently...

Yeah, that’s a pretty nasty one. If the tabs are turning into about:blank and they’re still sitting there as tabs, I’d suspect Firefox is losing the saved session information rather than simply closing the tabs.

I’d first check Recently closed tabs and, if you’re using Firefox on Android, also check the Inactive tabs section. Firefox can move older tabs there depending on your settings.

If this has happened three times, though, I wouldn’t keep assuming it’s user error. Make sure Firefox is updated and tell the forum exactly what Android/Firefox versions you’re running and roughly how many tabs you normally keep open. If Sync is enabled, check your synced tabs from another device too. Firefox does support syncing open tabs.

And I’d avoid clearing Firefox's data or uninstalling it while you're trying to figure this out. That could make recovering anything that's left behind a lot harder.

Yep, this is happening to me too. I closed FF and went to bed. I opened it in the morning and lost about 20 tabs. Happens every time I restart FF. I looked in Firefox help. It said I could go into History and click "Restore Previous Session" but that option doesn't exist. All I can do is look at History and restore 'some' of the tabs. Too many have disappeared.

I followed their next advice, went into Settings, Home and Startup, to select "Open previous windows and tabs". but it was already selected. So I turned it off, restarted FF and turned it back on. I still lose all tabs every time I restart FF.

I only realized this is persistent now, after restarting on day 2 of this issue. My FF automatically updates.