Why is workbox writing files to tmp/build instead of public on deployment?

If I run my build script locally, workbox writes files to the public directory:

```
> react-scripts build && workbox generateSW workbox-config.js

Creating an optimized production build...
Compiled successfully.

File sizes after gzip:

405.84 kB build/static/js/main.0a2b00bf.js
2.63 kB build/static/js/685.d490ac7a.chunk.js
831 B build/static/js/91.541a4e54.chunk.js
811 B build/static/js/153.7aa0b5d4.chunk.js
806 B build/static/js/832.8de07afe.chunk.js
733 B build/static/js/844.63deabe8.chunk.js
728 B build/static/js/580.d7932d4f.chunk.js

The project was built assuming it is hosted at /.
You can control this with the homepage field in your package.json.

The build folder is ready to be deployed.
You may serve it with a static server:

npm install -g serve
serve -s build

Find out more about deployment here:

https://cra.link/deployment

Using configuration from /root/workbox-config.js.
The service worker files were written to:
• /root/public/sw.js
• /root/public/sw.js.map
• /root/public/workbox-74969ce0.js
• /root/public/workbox-74969ce0.js.map
The service worker will precache 7 URLs, totaling 177 kB.
```

But during deployment, workbox writes the files to the tmp directory:

```
remote: > react-scripts build && workbox generateSW workbox-config.js
remote:
remote: Creating an optimized production build...
remote: Compiled successfully.
remote:
remote: File sizes after gzip:
remote:
remote: 405.84 kB build/static/js/main.0a2b00bf.js
remote: 2.63 kB build/static/js/685.d490ac7a.chunk.js
remote: 831 B build/static/js/91.541a4e54.chunk.js
remote: 811 B build/static/js/153.7aa0b5d4.chunk.js
remote: 806 B build/static/js/832.8de07afe.chunk.js
remote: 733 B build/static/js/844.63deabe8.chunk.js
remote: 728 B build/static/js/580.d7932d4f.chunk.js
remote:
remote: The project was built assuming it is hosted at /.
remote: You can control this with the homepage field in your package.json.
remote:
remote: The build folder is ready to be deployed.
remote: You may serve it with a static server:
remote:
remote: npm install -g serve
remote: serve -s build
remote:
remote: Find out more about deployment here:
remote:
remote: https://cra.link/deployment
remote:
remote: Using configuration from /tmp/build_b798eb87/workbox-config.js.
remote: The service worker files were written to:
remote: • /tmp/build_b798eb87/public/sw.js
remote: • /tmp/build_b798eb87/public/sw.js.map
remote: • /tmp/build_b798eb87/public/workbox-74969ce0.js
remote: • /tmp/build_b798eb87/public/workbox-74969ce0.js.map
remote: The service worker will precache 7 URLs, totaling 177 kB.
```

package.json

```
{
...
"scripts": {
"build": "react-scripts build && workbox generateSW workbox-config.js",
}
...
}
```

workbox-config.js:

```
module.exports = {
globDirectory: "public/",
globPatterns: ["**/*.{png,html,js,ico,json,txt}"],
swDest: "public/sw.js",
ignoreURLParametersMatching: [/^utm_/, /^fbclid$/],
runtimeCaching: [
{
urlPattern: /api/,
handler: "StaleWhileRevalidate",
options: {
cacheName: "my-api-cache",
expiration: {
maxEntries: 5,
maxAgeSeconds: 60,
},
},
},
],
};
```

file structure:

```
root
├── src
├── package.json
└── workbox-config.js
```

I have tried moving the workbox script to the heroku-cleanup script but that doesn't work. Same thing happens.

How do I get the workbox script to write to the files to the root directory on heroku?