Today, both my Windows PC, and my main Linux PC, had LT removed (along with various other addons)
I don’t know if this is a bug with the latest Firefox, perhaps someone else knows.
I enjoyed using your LT - it was very useful, thanks.
This is a Firefox issue and they are working on it ([FIXED] Certificate issue causing add-ons to be disabled or fail to install - Announcements - Mozilla Discourse).