Wrong menu position when used in shadow dom

Hello!
I am using different react components from different component libraries and react-select is the only one which does not fully work in web components with shadow dom enabled. In my case the menu of react-select has a wrong position. I tried similar components of other libraries that also render a menu, but I did not have any problems with them. So I guess that the calculation of the position of the menu is a bit buggy, especially when used in web components. Or maybe I am missing some property which could solve my issue.

You can check my code here: https://codesandbox.io/s/react-select-with-shadow-dom-and-menuportaltarget-n03fe?file=/src/ReactSelectElement.js

So is this a bug or is there some way I could fix my issue?

Start with the linked CodeSandbox, especially src/ReactSelectElement.js, and reproduce the menu-positioning behavior inside a shadow DOM. Compare the rendered position with the expected placement and determine whether an existing property addresses it; done means the menu is positioned correctly in the reported setup or the limitation is clearly documented.