I want to change my bank card information in icloud

See the articles Change, add, or remove Apple ID payment methods - Apple Support

https://www.apple.com/us-hed/shop/help/viewing_changing_orders

I’ve added a new card and upgraded my icloud storage subscription using it but i can’t remove the old one because of the error message “there is an active subscription that requires at least one payment on file”. I don’t get what this means exactly. I already have a new subscription using a different card, what is the old one needed for anymore? Also, the payment for the old subscription has already been done for the current month using the old card. Can someone please explain in more detail the process? Thank you.