MagSafe, Apple's magnet-based wireless charging and accessory system, may not be the killer feature of the iPhone 12 that we first thought.

That's because the magnets can wreak havoc with credit cards, passports, and key fobs, and in some cases leave marks. This is a warning from Apple itself, not from disgruntled iPhone 12 users.

Apple has released new support information about MagSafe, warning that the magnets in the system can cause problems with RFID chips and magnetic strips such as credit cards and security badges.

"Do not place credit cards, security badges, passports, or key fobs between your iPhone and the MagSafe charger. If you have a case that holds these sensitive items, remove them before charging or make sure they are not between the back of the device and the charger."

That's a bit odd, given that Apple has an official leather card holder that connects to the back of the iPhone 12 via a MagSafe connection. Apple does not mention this, but it is likely that there is some protection to ensure that credit cards placed in the leather card holder are not erased by MagSafe.

There are more MagSafe issues to be aware of, especially the circular MagSafe charger, which can leave an imprint on cases made of leather, silicone, or other soft materials; MacRumors has a reader's photo of a silicone He reportedly flagged a photo of an iPhone 12 case.

The imprint left on the silicone case does not look very attractive or grating, but it is not exactly ideal for those seeking to keep their new iPhone 12 case as natural as possible. Apple has yet to pose a solution to this problem.

Apple has issued another warning about MagSafe and heat. As with any other wireless charger, "your iPhone or MagSafe Charger may become slightly warm while charging your iPhone. To extend battery life, the software may limit charging above 80% if the battery becomes too warm.

Overall, MagSafe seems more convenient than Lightning in terms of ease of use, but these warnings may deter some iPhone 12 buyers.