iphone 6 no updates or Phone pe gpay not working

Have you update to iOS 12.5.5, the latest iOS security update for iPhone 6 ?

You should still be able to use PhonePE, PhonePE requires iOS 12.0 or later.

Have you update PhonePE to version 5.7.10?

PhonePE - AppStore:

https://apps.apple.com/in/app/phonepe-recharge-investment/id1170055821

Contact the developer.