Incompatibility with React.StrictMode

Hello and thanks for mobx and the devtools! :)

I'm trying to use the devtools in an app while using React's (relatively) new StrictMode. But I'm getting this error:

Warning: findDOMNode is deprecated in StrictMode.
findDOMNode was passed an instance of _class which is inside StrictMode.
Instead, add a ref directly to the element you want to reference.

The interesting thing is that it happens even when the devtools aren't mounted to a StrictMode tree:

<>
  <React.StrictMode>
    <TodoList todoStore={store} />
  </React.StrictMode>
  <MobxDevTools />
</>

I'm also able to reproduce the same issue in my real app.
Can anything be done about it? If not, we should at least have a note in the README.

Here's a codesandbox where you can see the issue: https://codesandbox.io/s/1jjgxvjzo?autoresize=1&expanddevtools=1&fontsize=14

Start with the linked CodeSandbox and reproduce the findDOMNode warning under React.StrictMode, including when MobxDevTools is outside the StrictMode tree. Inspect the devtools integration responsible for the warning. Done means removing the warning where possible, or documenting the limitation in the README.