Let me tell you all about a very annoying bug I discovered. I updated to iOS 15 the day it was released. I found it not to be good enough to use daily so I decided to downgrade. I erased my device using the IPSW then I restored from my archived iOS 14.6 backup I had saved on my Mac (along with an iCloud copy.) I went through the set up fine but the following day I tried to pay my coworker using Apple Pay. Any, and all (debit) cards I used to pay her directly or "reload" the apple cash card itself, failed. I received a red exclamation mark informing payment couldn't be completed. Hmm. Well, weird. I did the standard troubleshooting (including disabling my VPN), reboot, erase all settings, remove and add again cards. Nothing worked. Then I tried to turn off apple cash then re-enable. Problem started here.
When I went to enable apple cash, I would get, "Apple pay unavailable. Apple Pay services are currently unavailable. Please try again later." So at this point, the apple cash card itself is removed and apple cash is disabled. Again did troubleshooting. Nope. So then I erase my device, and restore from my iCloud backup rather than my Mac backup. Welp, exact same thing. Apple cash is enabled from the setup process as it's a prompt asking if you'd like to set it up, which i did. But again, when I go to pay someone, same issue. I then do the troubleshooting, and when I get to disable and enable again Apple Cash, it's again, "Apple pay unavailable. Apple Pay services are currently unavailable. Please try again later." Well, okay, maybe it's something to do with the backups, right? Maybe something corrupted? Before I go to erase my device, again, I attempt to transfer the .50$ i have on the card to my bank. Red exclamation mark. Welp.
Well no, it's not anything to do with my backups because I then erased my device using the IPSW and I set up my device as NEW, no backups. I set up Apple pay during the setup. Cool, let me go test it now. I go to send someone money (and yes, I tried in various amounts from $1 to $50, during all troubleshooting steps prior, and no, I haven't reached any limit. Yes, my identity is verified, and yes, i also tried to log out of iCloud then sign back in.) When I go to send $10 to someone, SAME issue. Well, okay, at this point I know it's not my backups 100%.
Cool, I call apple and get to the whole senior advisor and they have me screen record the issue. Send it over to engineers and they are still, "working on it."
I get the itch to try iOS 15 again. So I updated my device (not factory reset then download backup) and I go to turn on apple pay and it works. Ok, cool, let me send some cash. It worked! So now I'm suspicious. So, guess what I spend the next few hours doing? I reset my device thats on iOS 15, and i set it up as NEW, and I go to use apple cash - works 100%. Hmm, I'm not satisfied yet - so I go and erase the device and install iOS 14.6 again. I repeat the steps I mentioned in the first 2-3 paragraphs. Guess what - apple pay WONT work. So now I know my apple pay only works on iOS 15 (both as setting up device as new and setting it up from a backup after installing iOS 15). Okay, so now this makes me suspicious if something on the backend on Apple's side triggers Apple Pay to work only on iOS 15 after updating.
PS. This entire time, Apple Cash worked 100% on my work phone, on my Mac, on my iPad, and, get this: with my PAIRED apple watch with the affected iPhone 12 Pro Max. With all these devices, I was able to disable and enable again apple cash, multiple times - all success. But these other devices are NOT on iOS 15. They are on their respective latest OS.