If you own the Apple MagSafe Duo Charger and got your hands on the new Apple Watch Series 7, we have some bad news for you. Unfortunately, the accessory launched last year doesn't support the new smartwatch's fast-charging feature. You will need to use the Apple USB-C Magnetic Fast Charging Cable to top up the Apple Watch quickly. This might mean Apple plans to release a new version of the MagSafe Duo, which, of course, is an additional expense.
Source: MacRumors