Apple has significantly expanded its support document warning of the effects its devices can have on implanted medical devices.
In March 2021, Apple issued a support document that downplayed the risk the magnets in the iPhone 12 could have on such medical device:
"Though all iPhone 12 models contain more magnets than prior iPhone models, they're not expected to pose a greater risk of magnetic interference to medical devices than prior iPhone models," the document used to read. (You can still read a cached copy here).
The document recommended keeping the "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)."
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The updated document has been expanded and now recommends that the following products should be kept a safe distance away from a medical device such as implanted pacemakers and defibrillators.
The advice for safe distances remains the same: 6 inches/15 cm or more than 12 inches/30 cm apart if wirelessly charging.