This pertains to the availability of commit comments in a pull request.
As to my best knowledge, the above box appeared in the Files changed option in a PR, but it doesn’t show up now in any new pull requests made. With regard to the Pull Requests that were opened earlier, the box shows in only some of them.
Actually we are working on improvements for Perceval (which has an option to retrieve pull request data from Github), and have included a feature to retrieve also the commit comments present in a pull request as part of the retrieved pull request data. So wished to know whether Github has removed support for pull request commit comments or it is some other case that I might be missing on.
As a reference example, for the pull request present here, it would really be helpful if somebody could tell how the commit comments present in this pull request were made in the first place.