Security Vulnerabilities fixed in Thunderbird 78.10.2 — Mozilla

If a MIME encoded email contains an OpenPGP inline signed or encrypted message part, but also contains an additional unprotected part, Thunderbird did not indicate that only parts of the message are protected.
OpenPGP secret keys that were imported using Thunderbird version 78.8.1 up to version 78.10.1 were stored unencrypted on the user’s local disk. The master password protection was inactive for those keys. Version 78.10.2 will restore the protection mechanism for newly imported keys, and will automatically protect keys that had been imported using affected Thunderbird versions.