None of what was posted will fix this. For many of us, and it will be quickly obvious if you are one, the original address associated with a credit/debit card in iCloud or Apple Pay will be retained forever in iCloud. You can wipe your device, get a new one, set it up as new, etc., as soon as you log into your iCloud account that address will be back. I’ve done all of those as have many others, it will always come back. Either this doesn’t affect enough users to track this down or they are at a loss to figure it out.
Two options do work but both are somewhat tedious. For me the problem was only with one bank’s debit/credit card. I chose to get my bank to issue me a new card with a new account number to replace the old one. I went into the bank to make the request and the associate who was helping me took my phone and said “you can change the address in settings” and she proceeded to do so. And the address was changed. So she thought that I was good. I said just wait a minute and then I restarted my phone and the old address was back. She processed the request for the new card without further comment.
Since getting the new new card and deleting the previous one I’ve had no problems. When you go to add the card you will be shown the previous ones to select, just skip those. As you enter or scan the new one your address will be pulled from your contact card. Make certain that it only has the address you want used. And make certain that is the address that the bank has for you because that address is part of the verification process for Apple Pay with your bank. The correct address has remained now through multiple device restarts and multiple OSes. I consider myself cured. Fortunately for me this card was only listed as payment on one or two merchant’s sites so I was able to quickly make the changes.
The other option which I would have found to be extremely onerous is to create a new iCloud/Apple ID account and make that your primary on your Apple Pay devices. There would be a cascade of issues triggered by that so I opted for the new card. For me it was quite simple. Although I‘m assuming that if I move once again that I will have to do this once more. But I’m not going anywhere for a long time. But again for some reason the first address you associate with a card seems to be retained somewhere in iCloud forever. That is what they need to track down.