`npm run build` fails to compile on a fresh unmodified CRA app ("Class constructor Parser cannot be invoked without 'new'")

Describe the bug

Completely fresh and unmodified create-react-app app fails to build with npm run build. Error is Class constructor Parser cannot be invoked without 'new':

Did you try recovering your dependencies?

Probably N/A since completely fresh, unmodified output of initial npx create-react-app... command, but yep, I did try. Did not help.

Which terms did you search for in User Guide?

Had a glance through the build section again, searched Google, and searched issues here for the specific error.

Environment

  current version of create-react-app: 3.4.1
  running from /Users/janabeck/.npm/_npx/50873/lib/node_modules/create-react-app

  System:
    OS: macOS 10.15.6
    CPU: (16) x64 Intel(R) Core(TM) i9-9980HK CPU @ 2.40GHz
  Binaries:
    Node: 12.18.3 - /var/folders/pq/gd8qpx2s5b95t3jnvrrx0nh40000gq/T/fnm-shell-2477482/bin/node
    Yarn: Not Found
    npm: 6.14.8 - /var/folders/pq/gd8qpx2s5b95t3jnvrrx0nh40000gq/T/fnm-shell-2477482/bin/npm
  Browsers:
    Chrome: 85.0.4183.102
    Firefox: Not Found
    Safari: 13.1.2
  npmPackages:
    react: Not Found
    react-dom: Not Found
    react-scripts: Not Found
  npmGlobalPackages:
    create-react-app: Not Found

And my coworker’s, who verified the failure:

Environment Info:
  current version of create-react-app: 3.4.1
  running from /Users/robertharris/.npm/_npx/92901/lib/node_modules/create-react-app
  System:
    OS: macOS 10.15.6
    CPU: (16) x64 Intel(R) Core(TM) i9-9980HK CPU @ 2.40GHz
  Binaries:
    Node: 14.9.0 - /usr/local/bin/node
    Yarn: Not Found
    npm: 6.14.7 - /usr/local/bin/npm
  Browsers:
    Chrome: 85.0.4183.102
    Firefox: Not Found
    Safari: 13.1.2
  npmPackages:
    react: ^16.13.1 => 16.13.1 
    react-dom: ^16.13.1 => 16.13.1 
    react-scripts: 3.4.3 => 3.4.3 
  npmGlobalPackages:
    create-react-app: Not Found

Steps to reproduce

1. npx create-react-app foo
2. cd foo/
3. npm run build

I also tried npx create-react-app@3.3.1... to see if going back one minor version would change anything, but the result was the same.

Expected behavior

A fresh unmodified CRA app should build successfully.

Actual behavior

(Same screenshot as above.)

Reproducible demo

Pushed my fresh unmodified CRA app here: https://github.com/jebeck/cra-build-failure

So just clone, npm i, and npm run build. I have also tested on a 3rd machine (in addition to mine and my coworker’s) and I get the same failure.

[maxabrams]

+1. Has been working all day and recently (within the hour) began failing. Targeting specific, previous versions in package.json has no impact. We cannot build any React projects (new or existing).

[ai]

The fix was released in PostCSS 7.0.34.

If you want t say thanks for the quick night fix, our PostCSS Open Collective will be the best option