How is this new?
There are plenty of Chinese phones with high capacity batteries. My current Xiaomi 15t pro as a example has a 5500mah, 3.93vdc battery (that's 21.62wh).
And they just all shipping fine...
USPS has just introduced a $50 “misuse of hazmat labeling” fee with supporting context that could infer a much stronger parcel scanning process behind the scenes (since it’s presented as a ‘you wasted our time’ fee). I would hesitate to say that nobody will ever follow these instructions. More likely, someone scalper will take a sob story to the press after USPS makes an example out of them.