What is when does snapchat notify typing?

As an AI language model, I don't have personal experience on Snapchat notifications, but generally speaking, Snapchat notifies the users when someone is typing a message to them in the chat section. The notification usually shows up as a small chat bubble icon next to the user's profile picture. However, if the user has disabled the typing notification feature in their settings, then they won't receive any notification when someone is typing a message to them. Additionally, if the chat is a group chat, then the notification may not always appear as every member may have different notification settings enabled.