Why am I repeatedly asked to update my payment method on Apple devices?

See this, you might need to add a different payment method because you’re current keeps getting declined

Update your payment method on your iPhone, iPad, or Apple Vision Pro

1. Open the Settings app.
2. Tap your name.
3. Tap Payment & Shipping. You might be asked to sign in with your Apple Account.
4. If you need to update the billing information of an existing card, tap the payment method, then tap Edit.
5. Enter your new billing information, then tap Done.

If there's an issue, change your payment method

1. Open the Settings app.
2. Tap your name.
3. Tap Payment & Shipping. You might be asked to sign in with your Apple Account.
4. Tap Add Payment Method, enter the new payment method, then tap Done.
5. Tap Edit.
6. Tap the red delete button next to the old payment method, then tap Remove.
7. If you want, you can then re-add the old payment method with updated billing information.