The unfollow button will immediately unfollow the channel without confirmation. The unfollow button can appear as a heart on a stream, on a channel view, in the search list (for some reason?!), or the text "unfollow" in a user/message context flyout. Several times now I have accidentally pressed these buttons which frustratingly reset the "following at" date. I just want a clearly written confirmation modal with a prominent cancel button for all of these interactions, especially when the button is just a heart and can be mistakenly tapped in an unclear context.