It is my understanding that the leather sleeve has an integrated NFC chip, which can be read by the NFC reader on the iPhone 12. When your phone is inserted into the case, the iPhone knows that a sleeve was put on, and iOS will trigger an animation on the phone's display. More on discussions.apple.com

Bullstrap cases. There is nothing better. I’ve been using them for years. I currently have an iPhone 12 Pro. I’ve used Bullstrap since the X. The leather is real and the cases are expensive, you’ll understand why the moment you unbox the case and hold it in your hands. I switched back and forth between Bullstrap and Apple, and then when Apple added that god ugly plastic ring around the camera I never touched another one. The Patina is amazing, the smell is amazing, and buttons are amazing; the entire case is just quality and they last. They also have other great accessories such as Apple Watch straps and AirPod cases if you like to match all of it! Edit: Sorry, I don’t dislike anything about the case. If I had to choose something, I would like to pay less, but I do understand why they are so expensive and because of that I am fine paying for them. You can catch discounts from time to time. :) More on reddit.com

I have a black leather case on my pro max. Love the feel of the case and works well with my belkin magsafe mount. The other day, I dropped it face down in my kitchen and screen was ok. I do have a screen protector on but I think the lip is big enough that it prevented any cracks. The case did come loose so I had to readjust it. More on reddit.com

I have a Bullstrap. The cosmetic replacement warranty makes it a good deal if you keep your phone for two years and replace the case at least once. If you’re an annual upgrader, unless you’re really clumsy, it’s probably on the expensive side. Quality has been pretty good for me. More on reddit.com