If that happens to be the case, then each time you have a new message arrive on your WhatsApp account, and if the WhatsApp Web client is open on your computer, then the messaging app will send you a notification on your mobile device to inform you that the client is open, and there is an incoming message. At least this puts you on the alert, and it might help you prevent others from checking out your messages on your computer as clicking on said notification will close the WhatsApp Web client on your computer.
Pretty useful update feature, don’t you think so? At least your privacy will be more secure this time around.