This is because Apple has recently confirmed that its 29W charger will not work with the MagSafe Duo. Instead, customers will have to use a different charger, like the 30W model or the 20W model, which thankfully at $19 isn’t too expensive of a purchase, although for some it might feel unnecessary.
According to Apple, the reason behind this is because of the MagSafe Duo’s specifications which will require an adapter that supports USB Power Delivery 3.0, which the 29W model doesn’t have. The 29W model was actually replaced back in 2018 with the 30W model, which also seems to suggest that older charging adapters might not play nicely with the MagSafe Duo as well.
We imagine that there are going to quite a number of people upset by this, especially since chargers aren’t really something many of us see the need to “upgrade”. We’re not sure how many people have the 29W model lying around, but it might be something to think about if you’re considering getting your hands on the MagSafe Duo.