Tiny blue speech bubbles when I swipe right on a contact in chats.

I think it’s just to highlight messages or contacts that you need to remember to respond to. When I touch the icon, it put a blue dot next to the contact/conversation, and when I go away from messages it shows a “new message “ number on the message icon.

I will probably start to use this if I read a message but don’t have time to respond/respond fully, I can highlight it this way to catch my attention later.