Why is there a lead (Pb) warning on extra heavy duty batteries?
It's probably just a syndrome of someone buying the cheapest batteries on the market.

That has the effect of someone else producing the cheapest possible batteries.

That has the effect that someone had to send an image file to factory that prints the wrappers of the batteries, and that someone didn't have any engineer to talk to, so they just took the symbols they thought should appear on such a battery.