Magnet
Will phone charge if there is a flat magnet or steel strip between phone and case?
iPhone XR
Question marked as
Probably not as intended, or not at all, because that material can interfere with the waves and change its pattern or even completely block it.
It can also cause some overheating and severely damage your device... or worse.
Do not place anything between power sources and charging circuits that's not meant to be there (even more if it's metallic, which is conductive). It can be dangerous, expensive and even fatal.