When I go to Microsoft Entra ID in Azure, why does it say that I (Owner) am an External?

Hello, 

I am new to Azure and have been learning about Microsoft Entra now using my personal Microsoft account.

While I was browsing around, I went to Azure portal -> Microsoft Entra ID -> User. I see that I am the only user in the current directory (ex: "email address removed for privacy reasons" directory) which makes sense. 

However, what I am confused about is that I have User Principle Name as  "microsoftsutdent123_outlook.com#email address removed for privacy reasons" (although I checked that I am a global admin). I really don't get what's happening and even if this is normal, and I did deploy a very basic web app using Azure App Service if that matters... 

Could someone please clarify why this is the case or is this an error?