Comments now indicate if they were left by the author of the issue or pull request.
Draft pull requests
You can now signal to potential reviewers that a pull request is a work in progress by creating a draft pull request. Draft pull requests suppress notifications to CODEOWNERS reviewers and cannot be merged until they are marked as “Ready for review” in the merge box.
Draft pull requests are available for public and open source repositories, as well as in private repositories for groups using GitHub Team and Enterprise Cloud.
Learn more about draft pull requests on GitHub