I was on a thread about this issue that seems to have since disappeared. Immediately after updating to 15.4.1 I was no longer able to use my phone to read a continuous glucose meter and apple pay no longer worked. This was IMMEDIATELY after the update. I use my phone to read a medical device, as do millions of other people worldwide. Apple is pushing this technology for medical devices. I've done three factory resets - two at the store. When tested my NFC system says that it works. However, it no longer reads my device or Apple Pay at the cash register. From a variety of forums, I can see that this is an issue that is now frequently occurring when people update their operating system. My phone is less than two years old. I was offered no solution at the apple store other than purchase a new phone. It is quite frankly grossly unfair to suggest that I need to purchase a new phone due to a known issue. Apple is jeopardizing the health of millions of people who use wearable medical devices. Those who use Apple Pay could be left stranded with no way to pay for their purchases. Imagine traveling and attempting to use Apple Pay and becoming stranded in an unfamiliar place. This is not ok. It is NOT solved. It must be fixed.

The same thing happened to me when I updated to 15.4.1. I am so frustrated. I have an iPhone SE 2020 and it's not even two years old yet. I use my phone to scan a continuous glucose sensor. It worked absolutely fine all day until I did the update. Immediately after I did the update NFC no longer worked. I did trouble shooting over the phone. Then went into a store. At the store the rep assured me that my phone was absolutely great and nothing was wrong with it -- despite the fact that it no longer read my CGM. In the process I tried two different expensive sensors to isolate if the issue was the sensor or the phone. Two sensors didn't work. I then used my son's phone to scan the sensor and it did work. Mind you, these sensors are $70 each and due to this issue I had to waste two of them. Since then I've had to carry two phones with me, mine and my son's old crusty iPhone 7 just so I can monitor my medical device. After I went to the Apple store and was told my phone was fine, I went to the grocery store a couple of days later and attempted to use Apple Pay. It didn't work. I returned to the Apple store and by the time all was said and done, three factory resets were done on my phone and a dozen other trouble shooting steps. Finally the apple rep tried to make an apple pay transaction on my phone and it didn't work. Only then did they agree that my NFC was not working. I'm pretty peeved about this. I am barely out of warranty. I can't read my medical device. My only choice is to spend hundreds on a new phone, carry two phones or purchase an expensive dedicated sensor from Abbott pharmaceuticals. Adding a bit more salt to the wound, I see that Apple has a website set up to explicitly promote the usage of apple products to doctors, medical systems and patients. Apple: If you are going to market wearable medical technologies to us, they have to reliably work. There are people who could actually die from this issue. It is no joking matter. Please resolve this issue immediately, offer those affected a fix or an immediate free replacement. Our health and well being has been threatened by a buggy iOS update. This is dangerous in addition to being unfair.