TypeError: Invalid PostCSS Plugin found at: plugins[0]

```
rollup-plugin-postcss@4.0.0
rollup@1.32.1
next@10.0.7
```

**postcss.config.js**
```js
module.exports = {
plugins: ['tailwindcss', 'postcss-preset-env'],
};
```
**rollup.config.js**
```js
import peerDepsExternal from "rollup-plugin-peer-deps-external";
import commonjs from "@rollup/plugin-commonjs";
import typescript from "rollup-plugin-typescript2";
import postcss from "rollup-plugin-postcss";
import copy from "rollup-plugin-copy";
import image from "@rollup/plugin-image";
import resolve from 'rollup-plugin-node-resolve';

export default {
input: "src/components/index.ts",
output: [
{
dir: "build",
format: "cjs",
sourcemap: false
},
{
dir: "build/esm",
format: "esm",
sourcemap: false
}
],
preserveModules: true,
plugins: [
peerDepsExternal(),
commonjs(),
image(),
resolve({ browser: true }),
typescript({
useTsconfigDeclarationDir: true,
"jsx": "react",
}),
postcss({ modules: true, inject: false, extract: true, config: { path: './postcss.config.js' } }),
copy({
targets: [
{
src: "src/styles/_variables.scss",
dest: "build",
rename: "variables.scss"
},
{
src: "src/components/package.json",
dest: "build",
rename: "package.json"
}
]
})
]
};
```

**ERROR**
```
[!] (plugin postcss) TypeError: Invalid PostCSS Plugin found at: plugins[0]

(@/***/postcss.config.js)
src/components/Badge/badgeComponent.module.scss
TypeError: Invalid PostCSS Plugin found at: plugins[0]
```

To workaround this I just add `require` like so
```js
module.exports = {
plugins: [require('tailwindcss'), require('postcss-preset-env')],
};
```
But this is not working for the nextjs - [more info here](https://github.com/vercel/next.js/blob/master/errors/postcss-shape.md)

Start with postcss.config.js and rollup.config.js, then reproduce the reported error around rollup-plugin-postcss with the listed versions. Done means the shown configuration no longer raises the invalid plugin error, with the stated Next.js compatibility concern addressed.

Written by the indexing model from the issue text.