First Time Chatters
Allow the channel.chat.message
EventSub subscription to include if it is the first time the user has sent a message in the given channel.
We can see this with IRC but not EventSub.
I understand only broadcasters or moderators can normally see that directly from native twitch chat without extensions, so possibly a scope or moderator status would be required.
It would just be nice to retain that information because it is useful for streamers who might use chatbots to respond to first time chatters with a welcome message. Also it is useful for moderation tools to see if a flood of first time chatters are 'raiding', and let moderators using 3rd party chat clients be able to see the new chatters as well.