Where and how does Thunderbird store email passwords on Linux systems?

I wish to recover lost a SMTP password, but can't find a recent answer for this question. If it is stored in an sqlite file, observation shows the /home/$USER/.thunderbird/*.default/*.sqlite files are mostly encrypted, so in that case, also looking for some insight into the encryption used, and the location of the key needed.

As of now, it's stored in /home/$USER/.thunderbird/$RANDOM_STRING.default-release/logins.json

I don't know, however, what's the encryption used or the default master password when user didn't set one (maybe it's empty string or some default password hiden in the app code?). I can see it's at least encoded even without setting a master password, but in theory a hacker could probably access it with proper knowledge, so it's basically unprotected. IMO, the Thunderbird devs should start using the login keyring to protect these passwords even when a master password isn't set.

See: https://security.stackexchange.com/questions/8780/is-it-possible-to-easily-retrieve-thunderbirds-passwords-with-access-to-hdd?newreg=a4029c04cb954aedb4f60a9201574dc7#comment233382_8819