Reproduction link

https://stackblitz.com/edit/react-ts-2nwidc?file=App.tsx

Steps to reproduce

import * as React from 'react';
import { Skeleton } from 'antd';
import 'antd/dist/antd.dark.css';

export default function App() {
  return <Skeleton active />;
}

What is expected?

This was working before v4.21. In v4.20, it works. Demo.

What is actually happening?

The skeleton is white, and you can't see the animation. It looks very bad when rest of page is dark.

This bug did not exist in v4.20 - https://stackblitz.com/edit/react-ts-wrhkry