after update 2.20.1 auto login mechanism not working anymore

[Reis-A]

Describe the bug
after update 2.20.1 the auto login mechanism works for the admin panel, but not for my external imap domain.
(my setup standard domain external imap server. login via username@externaldomain and short username.
manual login is possible and works but credentials are not stored.

To Reproduce
Steps to reproduce the behavior:

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior
A clear and concise description of what you expected to happen.

Screenshots
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Please complete the following information:

• Browser: [e.g. chromium 100, firefox 100, safari 14, mobile]
• IMAP daemon: [e.g. courier, dovecot] groupwise
• PHP version: 8.1.9
• SnappyMail Version: 2.20.1