For some reason PowerBI does not accept GA4 as a connection, so my data is stuck in GA4. PowerBI does support Universal Analytics (UA), but I cannot find a way to convert my GA property.
Is there a way to do this or should I start over again and create a new property as UA?
PowerBI currently doesn't support GA4 as a destination because the underlying api is not product ready yet. See the response in the microsoft power BI community here: https://community.powerbi.com/t5/Desktop/Power-BI-Google-Analytics/td-p/1679530
For information about the api's and their current state: This is a link to the api documentation the plugin is using (for universal analytics): https://developers.google.com/analytics/devguides/reporting/core/v4
This is a link to the api documentation of GA4 (which is still in beta): https://developers.google.com/analytics/devguides/reporting/data/v1
Regarding a solution for your issue: