Apkmodsios.com Apple Watch Bands With Magnets May Cause Interference With Compass on Series 5 Models
In fine print on its website, however, Apple has indicated that Apple Watch bands with magnets “may cause interference” with the compass. This includes the Milanese Loop, Modern Buckle, and Leather Loop. Sport Bands, Sport Loops, Link Bracelets, Nike, and Hermès bands do not contain magnets.
Magnetic interference can affect any compass, so this is not an Apple Watch issue, but something to keep note of while choosing a band.