While GitHub prevents self-approval of PRs, it doesn't prevent a user from approving a PR they worked on. In some scenarios, this could allow for PRs to be approved with no outside review.

This action prevents any committers on a Pull Request from approving the PR. It can be used standalone (e.g. triggered by on all submitted Pull Requests in a repo), or as a Required Status Check.

Create a workflow file (e.g. .github/workflows/reject-self-approve.yml) that contains a step that has uses: peckjon/reject-pr-approval-from-committer.

The workflow using this action is supposed to be triggered by pull_request or pull_request_target event.

Here's an example workflow file:

name: Prevent committers from approving a PR

on:
  pull_request_review:
    types: [submitted]

jobs:
  preventapprove:
    name: reject PR approval by committers to the PR
    runs-on: ubuntu-latest
    if: github.event.review.state == 'approved'
    steps:
      - name: Dismiss code reviews from collaborators
        uses: peckjon/reject-pr-approval-from-committer@master
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}