[rob74]

It took a while for me to parse the title...

So the key takeaway is: if you have a pacemaker or an implanted defibrillator, don't put your phone in your breast pocket? But I imagine people are already told to avoid that, just to minimize the risk of radio interference? Of course, this turns a remote possibility of impacting the functionality into a near-certainty (if the magnet is strong enough).

BTW these iPhones are not the first phones that contain magnets. The Moto Z range, which has been around since 2016, has accessories ("Moto Mods") that are attached magnetically. The magnets are in the accessories, but since one backplate is shipped with the phone, most people will probably have that attached.