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 a protected 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 Request 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 required reviews have been set up to include repository admins, 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.