A new notification option will start rolling out next month. According to the news posted in the admin center, roadmap feature 57455 will be rolling out in December. It is a new way to recognize new members to Teams, but also another notification setting we need to train users to control if that's what they like. This feature will be on by default, and there are to my knowledge nothing admins have to do or consider. But update your internal documentation and training if you have them.You will find these settings under the usual notifications section in Teams settings, and your options are as "usual" "Banner and feed", "Show only in feed" and "off".