4.1.3 uBlock Origin - HorlogeSkynet/thunderbird-user.js GitHub Wiki

Apparently there is experimental Thunderbird 65+ support.
As of Thunderbird 68+, there are still some issues.

So this is something to keep an eye on. Also see 4.1 Extensions from the arkenfox user.js project.

uBlock is available for 91+ on ATN (addons.thunderbird.net), but it only addresses RSS feeds (not emails).