When you are a group, you can mention the other group members in a message by entering the @ symbol then selecting the name from the list shown.

When someone is mentioned, you will see the @ symbol & name of the member mentioned in the notification.

Everyone in the group chat will see the member's name as it is stored in their own devices (if custom names are stored, custom names will be shown). If the member is not added as a friend, they will see the member's persona name.

Note: When you are mentioned in a group, you will still receive notifications even if you have muted the group chat. However, if you have muted the whole persona, no notification will be received.