Why can GitHub Actions checkout the repository, when I specify contents: none permission?

Consider the code:

on:
  workflow_dispatch:


permissions:
  contents: none

jobs:
  job-1:
    name: Job 1
    runs-on: ubuntu-latest
    timeout-minutes: 5
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4

It succeeds, although permissions.contents: none remove the permission from secrets.GITHUB_TOKEN.