Comments are public by default, which will appear on the share back reports, and are posted to the Engage Cheers and suggestions feeds if enabled.
Use the drop-down menu to switch the comment to private if you wish to have a private conversation with other admins to collaborate on the feedback, without employees seeing the dialog behind the scenes. Private comments only live on the admin dashboard and are only visible to other administrators who can view the response or suggestion you are commenting on. They do not appear on share back reports or in the Employee Portal. Read this article to learn more.