Thanks for the info Joep, and glad to know this worked around the problem.
So in your case the the Dutch langpack was added to your profile directory on the 27th of October, at 18:44 local time. Do you remember when you upgraded to Ubuntu 20.10 ? Does this timestamp correspond to the first time you launched thunderbird after upgrading, by any chance?
Thanks for the info Joep, and glad to know this worked around the problem.
So in your case the the Dutch langpack was added to your profile directory on the 27th of October, at 18:44 local time. Do you remember when you upgraded to Ubuntu 20.10 ? Does this timestamp correspond to the first time you launched thunderbird after upgrading, by any chance?