Have you moved country? If yes, make sure this is one of the payment methods that you can use with your account, as listed in this support article: Payment methods that you can use with your Apple Account - Apple Support .
・Unfortunately the payment methods list is somewhat general and does not include individual brands of cards (I guess there are too many and are constantly changing). This thread is an example of where a person was not using an acceptable kind —> Why are my cards not supported on the MFI… - Apple Community Prepaid cards are not true credit cards.
・Read any footnotes in the article., plus more information here —> Payment method declining, bank reports no… - Apple Community
・If you are trying to use a payment method from another country you may encounter problems.
Note that the document only says which methods _are_ acceptable. Apparently certain types (usually a credit or debit card) _must_ also be present under certain situations such as when a subscription is involved.
Also review this article: If your payment method is declined in the App Store or iTunes Store - Apple Support