The OAuth authentication method isn't supported for this data source. Contact your admin.

Hi,

I am having a similar issue that started on 11/14/2022.  We had some PowerBI reports reading some excel spreadsheets on a Sharepoint Online site.  I tried using the web connector instead of the Sharepoint Folder and I was able to connect on a new Power BI report.  When we try to then modify the PowerBI report to use the web connector instead of the Sharepoint Folder connector, we are now getting the error "The OAuth authentication method isn't supported for this data source. Contact your admin"  Again, if  I do this in a new report, it works fine when published to the PowerBI service.  I appreacieate any help or direction you can provide.