Xamarin is not a Microsoft own tech per se, well actually it is since they bought it, however their crossplatform teams have always been about C++ and JavaScript (C++ rulez at WinDev, no matter what).
Actually I think it was more of a strategic move to "own" mono runtime and provide a starting point for Visual Studio for Mac (which is anyway being rebuilt).
The fact that Xamarin is now trying to be Swing for .NET 7, and still failing on Linux (if the community wants they should build it), and on macOS (using Catalyst instead of proper Cocoa APIs), doesn't seem it is getting that much love overall.
Specially now apparently we should all be using Blazor either directly on the browser, via Electron or WebWidgers as per their own marketing.
In the end it boils down that there are many UI teams, each of them trying to make a point of still being relevant to managment while fighting for resources.