On Black Friday the advertising was that I could upgrade to a iPhone 11 for 0$ ... both times it said 0$ and after I agreed to this, I was charged 375$ early upgrade fee which wasn’t stated ANYWHERE when I agreed to this
The early upgrade was for the previous device you got a subsidy for, you still had an outstanding balance that has to be paid off before you can do an early upgrade.
The advertisement was correct you would pay $0 upfront for the iPhone 11, but you still need to pay off what is owed on the previous device.
When processing the upgrade online it does show you at the bottom the one time fee if any.
It will also give you the breakdown at the end before you confirm the order.