NewMicrosoft Teams
Microsoft Teams: Chat for organizers and presenters in structured meetings and webinars
A new private chat feature for organizers, co-organizers, and presenters in Teams structured meetings and webinars allows event leaders to communicate separately from attendees before, during, and after events. This is a new capability with no negative impact on existing deployments.
Microsoft's description
Organizers, co-organizers, and presenters can chat privately in a separate chat from attendees. This chat is available to access before, during, and after the event.