Repository: create-react-app
Issue: Media URLs are incorrect in CSS
Labels: needs triage,issue: bug report

### Describe the bug

I am serving my app under a path such as `https://my-site.com/somePath`. When running a build I set the variable `PUBLIC_URL=somePath`, and I have also set `<base url="%PUBLIC_URL%" />` in `index.html` . This correctly updates the output files with the correct paths, except for URLs in the CSS, for example:

```
https://my-site.com/somePath/static/css/somePath/static/media/some-font.woff2
```

As you can see the CSS URL is incorrect and is not referencing the media directory _relative to_ the CSS file.

### Did you try recovering your dependencies?

<!--
  Your module tree might be corrupted, and that might be causing the issues.
  Let's try to recover it. First, delete these files and folders in your project:

    * node_modules
    * package-lock.json
    * yarn.lock

  Then you need to decide which package manager you prefer to use.
  We support both npm (https://npmjs.com) and yarn (https://yarnpkg.com/).
  However, **they can't be used together in one project** so you need to pick one.

  If you decided to use npm, run this in your project directory:

    npm install -g npm@latest
    npm install

  This should fix your project.

  If you decided to use yarn, update it first (https://yarnpkg.com/en/docs/install).
  Then run in your project directory:

    yarn

  This should fix your project.

  Importantly, **if you decided to use yarn, you should never run `npm install` in the project**.
  For example, yarn users should run `yarn add <library>` instead of `npm install <library>`.
  Otherwise your project will break again.

  Have you done all these steps and still see the issue?
  Please paste the output of `npm --version` and/or `yarn --version` to confirm.
-->

Yes, and likely not applicable.

### Which terms did you search for in User Guide?

<!--
  There are a few common documented problems, such as watcher not detecting changes, or build failing.
  They are described in the Troubleshooting section of the User Guide:

  https://facebook.github.io/create-react-app/docs/troubleshooting

  Please scan these few sections for common problems.
  Additionally, you can search the User Guide itself for something you're having issues with:

  https://facebook.github.io/create-react-app/

  If you didn't find the solution, please share which words you searched for.
  This helps us improve documentation for future readers who might encounter the same problem.
-->

Webpack, media, static, build

### Environment

<!--
  To help identify if a problem is specific to a platform, browser, or module version, information about your environment is required.
  This enables the maintainers quickly reproduce the issue and give feedback.

  Run the following command in your React app's folder in terminal.
  Note: The result is copied to your clipboard directly.

  `npx create-react-app --info`

  Paste the output of the command in the section below.
-->

Environment Info:

  current version of create-react-app: 5.0.1
  running from REDACTED/.npm/_npx/c67e74de0542c87c/node_modules/create-react-app

  System:
    OS: macOS 13.5.1
    CPU: (10) arm64 Apple M1 Max
  Binaries:
    Node: 18.12.0 - ~/.nvm/versions/node/v18.12.0/bin/node
    Yarn: 1.22.19 - /opt/homebrew/bin/yarn
    npm: 8.19.2 - ~/.nvm/versions/node/v18.12.0/bin/npm
  Browsers:
    Chrome: 117.0.5938.149
    Edge: Not Found
    Safari: 16.6
  npmPackages:
    react: ^17.0.2 => 17.0.2 
    react-dom: ^17.0.2 => 17.0.2 
    react-scripts: 5.0.1 => 5.0.1 
  npmGlobalPackages:
    create-react-app: Not Found

### Steps to reproduce

<!--
  How would you describe your issue to someone who doesn’t know you or your project?
  Try to write a sequence of steps that anybody can repeat to see the issue.
-->

(Write your steps here:)

1.
2.
3.

### Expected behavior

Media file URLs in CSS should be relative to the CSS file and not incorrect as shown above.

(Write what you thought would happen.)

### Actual behavior

Media paths are incorrect.

(Write what happened. Please add screenshots!)

### Reproducible demo

<!--
  If you can, please share a project that reproduces the issue.
  This is the single most effective way to get an issue fixed soon.

  There are two ways to do it:

    * Create a new app and try to reproduce the issue in it.
      This is useful if you roughly know where the problem is, or can’t share the real code.

    * Or, copy your app and remove things until you’re left with the minimal reproducible demo.
      This is useful for finding the root cause. You may then optionally create a new project.

  This is a good guide to creating bug demos: https://stackoverflow.com/help/mcve
  Once you’re done, push the project to GitHub and paste the link to it below:
-->

(Paste the link to an example project and exact instructions to reproduce the issue.)

<!--
  What happens if you skip this step?

  We will try to help you, but in many cases it is impossible because crucial
  information is missing. In that case we'll tag an issue as having a low priority,
  and eventually close it if there is no clear direction.

  We still appreciate the report though, as eventually somebody else might
  create a reproducible example for it.

  Thanks for helping us help you!
-->