To check for API usage, you should be the owner of the API Project on console.adobe.io then you can find that from "Insights'
However, when you are referring to the Adobe Analytics connector in Power BI, it could be using an Adobe-owned API project and you have no access.
As a side note, API data access is always slow from my point of view, you can observe that from the AA Workspace and see those spinners if you have a huge project.