The user has new Echo notifications about Flow threads.
When the user opens the notifications panel, turn the bubble from red to gray, to indicate that the user has now seen the notifications.
Everything else about the read/unread state should stay the same as current functionality. See mockup below.
When the user opens the notifications panel, there is a highlight on the items that are new since the last time the panel was opened. The blue highlight should appear and then fade, as seen in the mockup below.
Pau made a video showing how the highlight should work: https://www.youtube.com/watch?v=1u3M3qZ8N8s
Active users have said that getting individual Echo notifications for every active conversation makes them feel overwhelmed. If you don't want to look at every thread that you've got a notification for, then you either have to mark them all as read, open them in different tabs for later use, or just live with a red notification bubble. Leaving the red notification bubble promotes notification-blindness, and makes it less likely that users will actually pay attention to new notifications.