These cards may become unusable
Apple has provided further guidance on using the MagSafe Magnetic Wireless Charger for iPhone 12 smartphones.
On the issue of demagnetization, Apple has confirmed that credit cards and plastic card keys should not be placed between the back of the phone and the MagSafe charger, or these cards could become unusable.
Apple has also stated that you should not use a metal protective case or a thick protective case as this will affect the MagSafe charging performance. She may simply not charge the smartphone.
If you are using a leather protective case, a ring may be imprinted on the case when using MagSafe. This is due to the soft texture of the leather case and the powerful MagSafe and iPhone 12 magnets.
Wireless charging causes the phone to heat up. If the temperature is too high, the charging speed decreases and reaches a maximum after the temperature drops.