WhatsApp is developing a new feature called Username Key as a rebranding of the previously announced Username PIN with a clearer approach to functionality and control of personal messages.
Username Key can help reduce spam by providing additional control over who can contact a user via username. Users can also set a unique code that must be entered by first-time individuals who want to send a message through this channel.
This feature is optional, meaning it is not automatically activated. It is suitable for users who want to limit conversations to trusted contacts only. In addition, WhatsApp also plans to display a notification at the top of the Chat tab for users who have set a username but have not activated Username Key in an effort to raise awareness of this additional protection.
With this rebranding, WhatsApp emphasizes that Username Key is not an account security feature but rather functions as a chat access control. For now, it is still in the development phase and is expected to be introduced in a future update.