Microsoft Office 365 Activation Prompt Using Legacy Edge WebView Instead of Edge WebView2

jsobota 

We finally got a case opened with Microsoft on this. After working together to examine the behavior, they were able to confirm that the login was indeed using Legacy Edge WebView - but they detailed that this is working as intended/designed. They stated that the Microsoft 365 products like Office 365 and Teams, use the "Microsoft.AAD.BrokerPlugin" for the authentication process, and that plugin is currently only built to use the legacy edge webview engine and will therefore report the user agent string as Edge/18.X. There's no process to force it to Edge WebView2 as it isn't designed for that yet

They further detailed that there is no way to redirect the sign-in to a different method like a browser. 

If it helps anyone else, the way we confirmed what was being used by the system was by running a ProcMon monitor, examining the "Microsoft.AAD.BrokerPlugin.exe" process that runs when the signin window appears, and examining that stack determined it was calling edgehtml.dll which is legacy edge webview.