WhatsApp supports a lot of devices, but this line that has been followed so far is going to change. So old iPhone owners will not be able to have the app unless they upgrade to a newer version of iOS or get a new iPhone.
WhatsApp is getting ready to stop supporting old versions of operating systems for many different reasons. It's probably a must movement if he wants to adopt new ones possibilities which may not work on older OS versions.
There may also be some gaps security and bugs that can only be fixed in recent versions of operating systems. Such moves naturally turn some users off.
So the popular app will stop supporting two of the older versions of Apple's iOS, namely iOS 10 and iOS 11. This means that iPhone users will have to run at least iOS 12 to continue using WhatsApp. But the above change is not going to happen until October 22.
The application will stop working on some iPhones, especially those released in 2012 and 2013.
IOS 10 and iOS 11 will stop being supported on October 24, 2022.