*** WARNING ***

Anyone running Thunderbird 68.x.x , please be aware, automatics upgrades to 78.2.2 have now started.

This is highly likely a mistake by the development team, as the release notes for the latest version 78.2.2 state:

Thunderbird version 78.2.2 is only offered as direct download from thunderbird.net and not as an upgrade from Thunderbird version 68 or earlier. A future release will provide updates from earlier versions. Automatic updates are available for users already running version 78.0 or higher.

Add-on support: As of version 78.0, Thunderbird only supports MailExtensions. Your favorite add-ons may not have been updated for compatibility.

*** TURN OFF AUTOMATIC UPDATES TO THUNDERBIRD 68.x.x if you still want to keep your existing extensions working. ***