I only see the Administrative Mode warning under specific circumstances. If I run Microsoft Edge Development from my Start Menu, my Task Bar, the Home Page, or the Windows screen, it runs without a warning. Every time another program starts Microsoft Edge Development, such as my requesting a download of a program update, I see the Administrative Mode warning.
@gregmar - I also see this happen at times when another app/task opens Microsoft Edge as an Admin. Another example is with Windows setup and Windows Updates (in specific scenarios), due to Microsoft Edge being opened with Admin privileges from the app/task.
We're aware of this and it's being tracked, etc. No time line for a fix.