When the WinUI3 window of Windows App SDK 1.6 is launched, it will cause any window with the TOPMOST style of any other process to lose the TOPMOST effect

[XyyCare]

Describe the bug

When the WinUI3 desktop window is launched, any window with the TOPMOST style of any other process will lose the TOPMOST effect, but the TOPMOST style does not disappear.

Steps to reproduce the bug

1. Use Visual Studio 2022 to create a WinUI3 project, the development language is C++.
   

2. Upgrade the WindowsAppSDK version to 1.6 via Nuget.
   

3. When upgrading Windows App SDK, an error is generated, prompting that Visual Studio needs to be restarted, but the upgrade is successful.
   

4. After restarting Visual Studio, compile and run the project, the bug reappears.
   HelloWinUI3.zip

5. For example, if we start procexp and turn on Options-Always On Top, we can check the window style through spyxx. As shown in the following picture, we can see that the Explorer window has the focus, but the procexp window is TopMost, so the Explorer window can only be behind now.
   

6. Then we start the C++ WinUI3 Deskop window and the bug reappears. As shown in the following picture, click the Explorer window to give it focus, and then the procexp window and the spyxx property window are displayed at the back. If you click them again, the TOPMOST state will be restored.
   

Expected behavior

No response

Screenshots

No response

NuGet package version

WinUI 3 - Windows App SDK 1.6.0: 1.6.240829007
WinUI 3 - Windows App SDK 1.6.1: 1.6.240923002

Windows version

Windows 11 (22H2): Build 22621
Windows 11 (23H2): Build 22635
Windows 11 (24H2): Build 26100

IDE

Visual Studio 2022

Additional context

Downgrading to version 1.5 and clearing all dynamically generated files can be recovered.

I'm not sure if this is a WinUI3 bug or a WindowsAppSDK bug, so I raised issues in both projects.

See also: microsoft/WindowsAppSDK#4801