Thunderbird 140.13.0 is due on 21st July 2026, but the Thunderbird folks have trouble building it. So, according to the motto that was coined when Thunderbird was run by volunteers, not 50+ staff turning over 10+ million USD, it will ship when ready.
We depend on a correct Thunderbird build, so Betterbird is also delayed. On the positive note, we managed to ship the next version on the 20th of July 2026.