First up, for the time being, it's not possible to check via app. With that out of he way, let me show you guys how to check data usage and remaining data for a billing cycle for AirFiber of Airtel
Go to airtel.in and login using your number.
After logging in, click on top right and click on profile
https://ibb.co/LS2dxgc
After that, scroll down to see the data usage and remaining data
https://ibb.co/Sd6nzC0
Hope that airtel will soon bring it on the app too. Till then, this is the...