Hi,
(excuse my poor English)
It's not the first time this problem happens. It happened before last year:
Everytime package maintainers upgrade Thunderbird version before
upgrading Firefox version, it happens than Thunderbird stops working
with GMail, and stop working with some RSS too. The message in both
cases is (from "error console"):
server does not support RFC 5746, see CVE-2009-3555
To fix-it, package maintainers have to upgrade Firefox from 78.10 to
78.11 , and then Thunderbird will start working fine again. Or downgrade
Thunderbird again to 78.10, the same version that Firefox.
It would be nice if in the future Firefox packages upgrade the same day
or days before than Thunderbird, so Thunderbird doesn't stop working.
Thanks
Àlex