WASM: Virtual Keyboard - white screen and tab freezes on loading

On loading the example app in the browser it shows the Qt-Logo, after that the page turns white and the tab becomes unresponsive.

It works if the app is built for Windows.
It worked with Qt 5.14.0 Beta 2(emsdk 1.39.0).

I found a workaround for this problem:
Adding a fixed width and height for the Window seems to fix it.

...
Window {
    visible: true
    width: 640          // fix
    height: 480         // fix
    ...

 I attached the project to reproduce and the built wasm apps.