Thunderbird default profiles question

in my ~/.thunderbird directory I find I have several default profiles…
Three questions:
How do I know which is the working profile. Is it the one with -release extension? I ask because -release suggests an original rather than working.

How are new profiles created as I have some going back to 2016.

Should these be retained or deleted for good housekeeping or other reason?


In that “.thunderbird” directory, there is a file “profiles.ini”. The default profile is marked there with “Default=1”.

I think you can create a new profile with:

thunderbird -P

(run that from a terminal). But it is several years since I last tried that.