when I'm using PBI Desktop for Report Server I don't have a clear information in a context of which user I'm currently working.
I assume PBI Desktop uses Windows User when for example sends the report to Report Server (web browser is closed) - is that true?
What if I need to send a report to Report Server using e.g. a user from test domain (assuming my workstation is connected to non-test domain?
Can you please confirm whether my understanding is correct?
That is correct the default is to use the current Windows user account, you can use custom or basic auth if you server is configure for it though. For the Windows scenario is you want to run Desktop as a different user you have to right click on it and select 'Run as different user'.