Github Packages 403

Today I learned that Github Packages is not free for private packages. And I learnt it by getting a cryptic npm 403 error when accessing https://npm.pkg.github.com from npm.

After about 1GB of transfers for Github Packages, it will "run out of quota" and you'll get a 403. I thought it was an authentication issue, so I racked my brains on why the Github Access Token was not working. But an authentication error will give you a 401.