However, it seems that Apple might have had a change of heart (pun intended) because according to MacRumors, Apple has since updated its support document in which they caution that MagSafe could have the potential to interfere with implanted medical devices like pacemakers and defibrillators.
According to the updated document, “Medical devices such as implanted pacemakers and defibrillators might contain sensors that respond to magnets and radios when in close contact. To avoid any potential interactions with these devices, keep your iPhone and MagSafe accessories a safe distance away from your device (more than 6 inches / 15 cm apart or more than 12 inches / 30 cm apart if wirelessly charging). But consult with your physician and your device manufacturer for specific guidelines.”
However, at the same time it seems that while Apple does acknowledge that the iPhone 12 has more magnets compared to previous iPhone models, the company still believes that they are “not expected to pose a greater risk of magnetic interference to medical devices than prior iPhone models”.