Over the last several hours, reports are being posted from users worldwide that Firefox has disable all or nearly all of their add-ons. I’ve lost all my add-ons except one. What a mess!
The Firefox team indicates it is apparently due to an expired intermediate cert. They are working on a fix.
https://bugzilla.mozilla.org/show_bug.cgi?id=1548973
Win10 Pro x64 21H2, Win10 Home 21H2, Linux Mint + a cat with 'tortitude'.