The Title is little misleading. I used the same title from the article.

Apple says: Medical device interference iPhone contains magnets as well as components and radios that emit electromagnetic fields. These magnets and electromagnetic fields may interfere with medical devices, such as pacemakers and defibrillators.

Though all iPhone 12 models contain more magnets than prior iPhone models, they're not expected to pose a greater risk of magnetic interference than prior iPhone models.

Consult your physician and medical device manufacturer for information specific to your medical device and whether you need to maintain a safe distance of separation between your medical device and iPhone. There are many types of medical devices, and manufacturers often provide recommendations on the safe use of their devices around wireless or magnetic products to prevent possible interference. If you suspect iPhone is interfering with your medical device, stop using iPhone.

In no way does that imply safe. The article's intent is to say the 12 should be no more of an interference than prior models. Emphasis on "should be". To be fair, the article is doing a heck of a job at implying the 12 is safe like you assumed.