It has to fit the thread
A new bottle that needs its own lid is a new inventory of spare parts nobody will stock in five years. If it cannot take the existing cap, it does not get made.
One material, named
If we cannot write the material on the page in plain words, it is the wrong material. That rules out most composites and every unnamed coating.
The wear part must be buyable
Gaskets, lids, straws and base covers are catalogue items with their own page, not warranty exceptions.
It must survive the dishwasher
Bodies go on the top rack and come out unchanged after five hundred cycles, or the finish is wrong.