In the older versions of the app, there was only one notification icon, no matter how many messages arrived from multiple contacts. While the primary behaviour still remains the same, there is a subtle change that is now being noticed by users. Multiple WhatsApp notification icons appear on the notification bar corresponding to the number of contacts/groups those messages have come from. But this is visible only for a brief while and appears behind the heads-up notification and disappears as soon as you swipe away the notification.
It is, however, still unclear if that is indeed a feature or just a bug as its blink-and-you-miss-it behaviour allows very little practical use.
