Thunderbird constantly asks for password after enabling 2FA on web.de/gmx.de

Hi everyone, since I enabled two-factor authentication (2FA) on my email accounts at web.de and gmx.de, I can no longer use these accounts reliably in Mozilla Thunderbird. I set up the accounts using an application-specific password (a so-called "one-time password"), as provided by web.de/gmx.de when 2FA is active. The initial setup works, and I can send and receive emails for a short time. But shortly after, Thunderbird asks me for a new password again — and this keeps repeating. I also tried using my regular account password, but of course that doesn’t work either, since Thunderbird has no way of entering the second authentication step required by 2FA. Interestingly, everything works fine on my smartphone with the Bluemail app. There I can use the application-specific password permanently without any issues. Does anyone have an idea what's going on? Could it be that Thunderbird doesn’t properly store or maintain sessions for app passwords? Or is there another workaround? Thanks in advance! Technical details (unchanged during setup): '''Incoming Mail:''' '''Server type:''' IMAP '''Server:''' imap.web.de '''Port:''' 993 '''Security:''' SSL/TLS '''Authentication method:''' Normal password '''Outgoing Mail:''' '''SMTP server:''' smtp.web.de '''Port:''' 587 '''Security: '''STARTTLS '''Authentication method:''' Normal password