Bug: Cannot cast some of the UWP activation arguments using dotnet as operator

[lhak]

Description

This is related to https://github.com/microsoft/microsoft-ui-xaml/discussions/9983#discussioncomment-10708446

When publishing a UWP project using the preview .net 9 support with AOT, I noticed a crash when an appservice from a win32 helper tries to connect. It turns out that casting the argument (args.TaskInstance.TriggerDetails) in the BackgroundActivated(BackgroundActivatedEventArgs args) activation method to AppServiceTriggerDetails fails using the dotnet as operator. However, it works using args.TaskInstance.TriggerDetails.As<AppServiceTriggerDetails>().

Steps To Reproduce

A project that uses background activation through an appservice with a win32 helper is needed. The project also has to be published with AOT in release mode by creating an msix package (it sometimes worked in Debug configuration).

Expected Behavior

Casting using dotnet operator should work

Version Info

cswinrt 2.1.16 dotnet 9 rc2

Additional Context

No response