[Problem/Bug]: When opening a Pdf file for the first time by attaching source or nagigate, a black render appears before loading the pdf reader

[thanhbao1996]

What happened?

When I add webview2 to Winform, then open a pdf file path, the form's background turns black after showing the pdf reader. This phenomenon only appears the first time. If you open the pdf file next time with different pdf files, it will not appear.

Importance

Blocking. My app's basic functions are not working due to this issue.

Runtime Channel

Stable release (WebView2 Runtime), Prerelease (Edge Canary/Dev/Beta)

Runtime Version

126.0.25.92.102

SDK Version

No response

Framework

Winforms

Operating System

Windows 10

OS Version

Enterprise LTSC 1809

Repro steps

1. Add webview 2 to the form with the source attribute being empty
2. Create textbox to input pdf and button to open pdf. Use Source assignment for webview 2 (you can also use Nagigate)
3. phenomenon of rendering black background and then loading pdf viewer.
   Note: It only appears the first time, it doesn't appear the next time

Repros in Edge Browser

No, issue does not reproduce in the corresponding Edge version

Regression

No, this never worked

Last working version (if regression)

No response

AB#53949887

[monica-ch]

@thanhbao1996 Can you share a simple sample app with the repro for us to start investigating the issue.