Your picture indicates the authentication method is 'normal password'. Change it to OAuth2, for the incoming and outgoing, in Tools/Account Settings, and check that cookies are accepted in TB Preferences. Restart TB and enter the account password in the OAuth window to allow TB access.

I had the same problem with a GMail account. After changing the authentication method to OAuth2 I got a popup requesting permission for Thunderbird to access the GMail account. Once that was done it started working again.