Power BI report data source authentication type changes when uploaded to Power BI report server

Hi,

I am new to Power BI server. I have created simple power BI report with SQL server database as data source using power BI desktop.

Here I am using authentication type as Database.

Till here everything is fine!!!

Now I uploaded this report on Power BI Report server, it got uploaded successfully.

But when I tried to open this report from report web portal it shows :

When I checked Data Sources tab from Manage option (In Report server), the authentication type is changed to Windows (It was 'Databse' when created)

What is the issue? Did I miss something while uploading?

Thanks in advance.

NOTE : If I change authentication type from Power BI Report server then report is working fine.

Report Server details :

Power BI Desktop details :