OAUTH request with outdated URL

Two months ago I switched from a NabuCasa URL to a Duckdns URL.
External URL is up to date and callback URI at Withings oauth application is up to date.
But when re-authenticating the integration, HA is still requesting with the old nabucasa URL.
The Integration has already been removed incl. auth information and reinstalled. What else can I do or check?

I get it to work by adding the external URL to the configuration.yaml