https://wccftech.com/iphone-12-user-discovers-magsafe-collects-iron-from-sand/

Apple's introduction of MagSafe on the iPhone 12 series gave room to a plethora of third-party manufacturers to launch their own set of innovative products. Apple's MagSafe charger magnetically attaches to the back of the iPhone 12 and delivers fast charging speeds. However, since the iPhone 12 has a set of magnets arranged in a concentric circle, it will attract metal that comes in close proximity. An iPhone 12 Pro user faced a similar fate as the device attached iron from the sand in Tahoe.

The iPhone not only gas magnets for MagSafe purposes, but also in the camera module and other areas. A user on Reddit posted a picture of his iPhone 12 Pro that appears to be covered in ferrous debris (via AppleInsider). The metal from the sand was magnetically attached to the MagSafe magnets, the optical image stabilizers in the camera module, and other areas while the rest of the device remained clean.