Mangenta Max, doesn't have more discount for Upgrade the device?

To clarify the OP’s question:

Trade in - most plans qualify for trade in of your old phone. You can see what your trade in is worth when you select "Upgrade" and shop for a new phone. At least for iPhones, Tmobile standard trade in values are lower than what you can get from Apple.

Device Upgrade - this use to be available to many legacy plans but with the recent 5G plans and the elimination of "price for life", only the new 5G plans offer a promotional trade that makes the upgrade cost nearly zero. However, the new 5G plans cost more per month than most legacy plans so you have to run the numbers to see which option costs less in the 2 years that you have to commit. Also note that once you leave your legacy plan, it's a one way ticket and will be lost forever the moment you agree to change.

My legacy plan goes all the way back to "One" plan and the last "free" upgrade I got was for my current iPhone 14 Pro. When 15 launched I was no longer offered the promotional device upgrades. Personally I'm not upset since the promotional upgrades was never a standard feature of my legacy plan so I took advantage of it with the expectation that it would not last much longer.

From here on out I am going back to just buying straight from Apple and get whatever trade in that Apple offers. So far I've been lucky that my legacy plan rate hasn't changed, but I'm sure that's also not going to last so I want to be free of financial entanglements from Tmobile (unpaid balance, promotional credits, early termination penalties etc) when that happens so I can shop around for the best deal, especially the ones that will shower me with all kinds of up front promotions as a "new" customer.