WhatsApp will no longer work on some older smartphones from January 1st

If you have an older iPhone or Android phone, you could completely lose access to WhatsApp or some features in the messaging app from January 1, 2021.

The makers of the messaging app have confirmed that support for older devices will stop in the new year, and for some it may mean that the app will stop working completely. You will only be affected if you do not have iOS 9 or higher on your iPhone or Android 4.0.3 or higher on your Android device.

Source