Bug: Events in shadow dom get duplicated when bubbling

Events dispatching from inside a shadow-root will be handled multiple times while bubbling up the virtual DOM tree. I suspect this is because of event retargeting when crossing the boundary of the shadow dom. React version: 17.0+, including 18-rc2 ## Steps To Reproduce Click on the button in the code example below: https://codesandbox.io/s/react-shadow-dom-event-doubling-msgnj1 ## The current behavior `onDivClicked` is called twice per click on the button. ## The expected behavior `onDivClicked` should only be called once per handled click.