Apple Card declining due to zip code when zip code is correct

I can see that this question is asked a lot on these forums but I haven't seen a good answer. My card always worked online and I've had it stored in my phone (Pixel, not iPhone) and on both my iPad and iMac. Recently it's started declining with a warning that the zip code doesn't match. I haven't changed my zip code, it's still the same one listed in my Apple Wallet, and it declines whenever I try to buy something online whether it's in Safari (iMac, iPad) or Chrome (Pixel, iPad).

What's up with this? How do I fix it?