Using ReactDOM.unstable_createRoot, clicking a label does not toggle the related checkbox.

It may not be appropriate to submit this as React concurrent mode has not been officially released but anyway here goes.

### Are you submitting a **bug report** or a **feature request**?
Bug report.

### What is the current behavior?
Using ReactDOM.unstable_createRoot, clicking on a label does not toggle the related checkbox/input. One can double click a label to toggle the checkbox. Clicking the actual `` works as expected.

### What is the expected behavior?
Using ReactDOM.unstable_createRoot, single clicking a label toggles the checked state of the related ``.

### Sandbox Link
https://codesandbox.io/s/react-final-form-simple-example-f2ojr?fontsize=14

### What's your environment?
The codesandbox.io link above. Forked from the "Simple Example".

### Other information
Nope.