Microsoft EmployeeHi Rene,
There's a lot going on here and a lot of things that are likely not going to work unless you build a custom connector. For a start it looks like you're trying to make POST requests to a source that needs authentication and you're connecting to a source that uses OAuth2 (?) authentication, both of which require a custom connector (https://blog.crossjoin.co.uk/2021/08/29/connecting-to-rest-apis-with-oauth2-authentication-in-power-query-power-bi/); and you're calling Web.Contents in a custom column and getting the url to call from another column in the same table (which is a dynamic source - you won't know what the url up front); and you're calling OData.Feed with a dynamic url too (this solution might help: https://blog.crossjoin.co.uk/2023/01/15/using-odata-feed-and-the-query-option-to-avoid-the-dynamic-data-sources-error-in-power-bi/). This is going to be a very tough problem to solve...