Export report as thin file

We are currently struggling with the following issue:

When we do an export report in group API call, there is no choice to select the downloadType (0 = including the dataset / 1 = just the thin file) this is at least what the browser does when I choose what kind of .pbix I want to have in the UI of the Power BI Service

https://learn.microsoft.com/en-us/rest/api/power-bi/reports/export-report-in-group

When I run the API call however, there is no body to do this and also in the URL it does not work.

Why do we want that? I am trying to download only the report of a dataset that has 500 MB and the API call does not go through ( it is too large)

What else we have tried:
Cloning the report - which leads to the same problem, the dataset is still tied to it.

preferClientRouting also did not work

Any ideas?