WebView2 control fails to load content in WinUI SampleBrowser

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### Describe the bug

When running the WebView2 control inside the SampleBrowser application, the content does not load. However, when running the same control in a standalone sample project, it works correctly.

[samplebrowser-winui.zip](https://github.com/user-attachments/files/32002780/samplebrowser-winui.zip)

### Why is this important?

We are currently using webview2 control in our application and we face an crash due to this .

### Steps to reproduce the bug

- Extract the attached project files.

- Open the WebView folder.

- Run the sample from within the SampleBrowser.

- Observe that the content is not displayed.

### Actual behavior

When running the sample inside the SampleBrowser, the HTML content is not displayed, even though the background color is applied.

### Expected behavior

When running the sample inside the SampleBrowser, the HTML content must be displayed.

### Screenshots

_No response_

### NuGet package version

1.0.4191.47

### Windows version

_No response_

### Additional context

_No response_

Start with the attached samplebrowser-winui.zip and the WebView folder, then run the sample from within the SampleBrowser to reproduce the loading failure. Compare its behavior with the same control in a standalone sample project; done means the HTML content displays inside SampleBrowser while retaining the applied background color.

Written by the indexing model from the issue text.