Why is a function I expect to be shaken from a tree still there on a create-react-app build?

Similar to Tree shaking create-react-app? but more of how to validate and fix.

So I have a created a library of react hooks. In there I added an example to help me understand how tree-shaking would work.

import { useClock, useDeepState } from '@trajano/react-hooks';
export function App(): JSX.Element {
  useClock();
  useDeepState("foo");
  return <div>Hello world</div>
}

However, there’s a function called useAsyncSetEffect that I added in my library code base, but tracing through the code for useClock and useDeepState I don’t hit that function at all, but when I look at the generated files I see a reference to useAsyncSetEffect.

Not really sure what’s causing it, the library isn’t large so the size is just a K gzipped, but I am curious as to why it is being included.