Element in WebView would lose focus when cursor moves out WebView area

Description
Elements in WebView would lose focus when cursor moves out WebView area, but in Edge, it would not happen:

In most cases, this issue would not be important, but while using ::-webkit-scrollbar in CSS to custom the style of scrollbar in web page, this issue would be unbearable because it would affect the normal use of scrollbar.

Version
SDK: Microsoft.WindowsAppSDK 1.3.230602002
Runtime: 114.0.1823.51
Framework: WinUI 3
OS: Windows 11 Pro 22621.1848

Regression
Was this working before but has regressed? no

Repro Steps

1. Create one empty project with WebView 2 through Template Studio;
2. Create one local HTML file to be mapped, or just open codepen.io;
3. Input the code from the screenshot as content;
4. Operate as shown in the screenshot.

Expected behavior: second screenshot
Actual behavior: first screenshot