Cannot connect to Home Connect integration

I tried to configure the integration with Home Connect with the documentation, but when it tries to open the web page it uses an incorrect URL for my installation.

https://api.home-connect.com/security/oauth/authorize?response_type=code
&client_id=9999
&redirect_uri=https://my.home-assistant.io/redirect/oauth
&state=99999

The external URL is correctly configured in HA. Also the redirect URL at Home Connect.

What am I missing?