I just happened to have the same bug (well, I think it is the same one),
impossible to start firefox, but the same problem was met with
firefox-esr and thunderbird (none can start). Downgrading each of these
ackages didn't solve the problem, thus leading to a problem from a
common library.
By chance, I know that everything was working fine yesterday, and that
only few package upgrades had been done meanwhile. Long story short, I
downgraded back all possibly related packages until finding back the
culprit.
Both firefox and thunderbird are working again when downgrading sqlite3,
libsqlite3-0 and libsqlite3-dev from 3.31.0-1 back to the testing
version 3.30.1+fossil191229-1
Raphaël
