CodePudding user response：
GitHub has an option for this in the branch protection settings, which is “Dismiss stale pull request approvals when new commits are pushed.” That controls whether the approvals are removed, and while it doesn't specifically re-request approvals from the reviewers, they will receive the normal notifications that changes have been pushed, and they can choose to re-review when it's convenient. Of course, the submitter can always click on the button to explicitly request a re-review.
Note that, as mentioned in the comments, there are various reasons to allow this practice, since sometimes there are minor improvements that could be made, but the status quo would be acceptable nevertheless. However, in some environments, this cannot be allowed for compliance or policy reasons, so this option exists for those cases.
