Instagram allows users to manage who can comment on their posts. This includes the ability to block comments from specific people. Blocking comments from a user is different than blocking the user entirely. When you block comments from a user, they will still technically be able to leave comments on your posts, but only the commenter will be able to see them. That is, the commenter won’t be notified that their comments are blocked, so they won’t know that the original creator and other users can’t see them.