What is billdeskpg.appleservices@hdfcbank?

I am guessing you are in India where the payment system used with Apple is routed through UPI which in turn uses Net Banking which in HDFC bank in turn uses. That is described in https://support.apple.com/HT212781 and in this old thread https://discussions.apple.com/thread/252370366?sortBy=oldest_first and on HDFC's web site https://www.hdfc.bank.in/ways-to-bank/digital-banking/online-banking/netbanking

If you are using HDFC Bank then it is a payment for something you purchased from Apple.

https://support.apple.com/HT210618

“What can be labeled as Apple Services transactions

Music, movies, TV shows, stickers, books, and app purchases (from the iTunes Store, App Store, and Book Store). These are billed at the time of purchase. They can also include in-app purchases, pre-ordered music or movies, and subscriptions that automatically renew.”

Is your payment method for your Apple Account the credit card issued by the HDFC banking institution?