I think I found the problem, this is a log entry from the error:
Password login via OIDC-conformant clients with externally-hosted
login pages is unsupported. Alternatively, login could have been initiated
from the wrong place (e.g., a bookmark).
The thing now is, I am not entering the user name and password on an externally hosted page, perhaps there is a setting that can help me here.
Thanks a lot