Strong magnets used in newer portable electronic devices can interfere with the function of implanted cardioverter defibrillators known as ICDs.
Resources
https://newsroom.heart.org/news/magnets-in-newer-portable-electronic-devices-can-interfere-with-implanted-defibrillators
https://www.ahajournals.org/doi/abs/10.1161/CIRCEP.121.010646
https://www.ahajournals.org/doi/10.1161/JAHA.121.020818