What miraculous change was made to the post-72 Marlin 1895 45/70, that prompts Buffalo Bore Ammunition Co to specifically state that some of their ammo should only be used in said guns?

https://www.buffalobore.com/index.php?l=product_detail&p=328

In 1972 Marlin chambered the modern round bolt 336 action in 45/70 and marketed it as a model 1895. The original 19th century model 1895 was a weaker square bolt action designed for black powder pressures. They are completely different rifles despite the model number.