Often a user in chat will post an objectionable message which the streamer and moderators miss: there may be an offensive meaning which is objectionable but cleverly concealed and a violation of channel-specific rules, for example.

I suggest adding a "flag" icon that works very much like the existing Reply button on every chat message whereby people in chat can select another chat message and post a reply message into chat which will be visible to channel moderators, chat bots with moderator status, and the streamer, Only, and non-moderators cannot see the reply.

This way there would be a safer means of communicating from other chatters than posting publicly, and a more efficient moderation response than trying to discuss with viewers using whispers.