Welcome to the forum.
You should contact support. They should replace it for you.
It’s not really charging extra, it’s just breaking it out as an option. Some people already have suitable USB-C chargers, since they are used for many laptops these days. If Framework just included it, and it wasn’t optional, then the price of the laptop would have to be higher. While some of the cables have an issue, the charger is quality and not cheap. Someone made a video of the charger being disassembled and analyzed piece by piece
youtube.com/watch?v=XyG8QEe6GIk