webengine simple browser cannot load the flash

we test Qt’s demo in Examples\Qt-5.12.6\webenginewidgets\simplebrowser on windows 10 platform，after the simple broswer running, enter the url: https://helpx.adobe.com/flash-player.html ,found that in the version 5.12.1/5.12.4 the flash can be load correctly, but in the version 5.12.5/5.12.6/5.13.2, the flash cannot be loaded.