My iPhone is not supporting WhatsApp update

An iPhone 7 running iOS 15, should be able to run WhatsApp. According to the App Store, WhatsApp requires iOS 12 or higher. On your iPhone open the Settings App > General > About > Version and let us know what the current iOS version is on your iPhone.

That’s a shame.

What did WhatsApp say when you asked them about why they dropped support for older iOS versions?