Very interesting - a disproportionately high amount of labor on our install was spent cutting and fitting pieces for all the various roof plane changes and edges, and it sounds like this is a solution to some of that by having pieces pre-made for more of these circumstances.
I haven't seen any mention of this before, so it might be a very new update, so probably worth getting some more info from Tesla. That said, I would certainly think they are using something that will hold up for 25 years, assuming the warranty is still the same.
Maybe the steel is to use all the scrap from cybertruck....