upgrading firefox-esr from 78.6 to 78.9 results in non-working firefox

[Eric S Fraga <e.fraga@ucl.ac.uk>]

Hello all,

I don't frequently upgrade if my system (mostly Debian testing) is
working but my bank told me that my browser was out of date and I needed
to upgrade.

So, I did 'apt update' and 'apt install firefox-esr' to upgrade from
version 78.6 to version 78.9.  Start up the new version and not a single
site I tried worked.  Just blank pages.

Reverted to 78.6 and it works just fine (although the bank is not happy
with me...).

I've checked the Debian bugs list but did not see anything relevant
(although there are so many bug reports that it's easy to miss one...).

I don't have time to do much more investigating at the moment but
thought I'd post this just in case anybody else has had the same
behaviour.  I'll hopefully investigate more in a few days.

Thank you,
eric

-- 
Eric S Fraga via Emacs 28.0.50 & org 9.4.4 on Debian bullseye/sid