Board Thread:New Features/@comment-43596541-20200821135532/@comment-1038387-20200821140958

Comments are not part of the MediaWiki portion of the site, so they wouldn't show up on WikiActivity either. On Legacy, comments showed up in Recent Changes. What you're describing isn't a RC/WA problem. They're looking for moderation alternatives for that.

The new Recent Changes may not cover all the use cases of WikiActivity, it's still improved in functionality to the old Recent Changes.