Required reviews ensure that pull requests have at least one approved review before collaborators can make changes to a protected branch.
Repository administrators can require that all pull requests receive at least one approved review from someone with write or admin permissions before they're merged into the default branch. For more information, see "About protected branches."
When required reviews are enabled, anyone with access to the repository can approve changes in a pull request. However, to merge your pull request you need someone who has write or admin permissions in the repository to approve your pull request's changes in their review.
If a person with admin permissions chooses the Requests changes option in a review, then that person must approve the pull request before it can be merged. If a reviewer who requests changes on a pull request isn't available, anyone with admin or write permission for the repository can dismiss the blocking review. For more information, see "Dismissing a pull request review."
Unless repository admins have been made to require reviews in repository settings, people with admin permissions can merge a pull request regardless of reviews from other admins.
You can't merge a pull request into a protected branch until someone with write or admin permissions approves it. If there are pending or rejected reviews, you'll receive an error message:
remote: error: GH006: Protected branch update failed for refs/heads/master. remote: error: Changes have been requested.