Where does Camphor flavor in Puerh tea come from?

„Prickling, Tingling, Numbing
Ancient tea trees are all over 100 years old. Their ability to resist natural problems; diseases and infestations is high. This variety of tea tree has existed in this habitat for thousands of years. These trees are already extremely resilient and the environment in which they are growing has mostly been left in untouched. There is no need for tea farmers to use agro-chemicals. But where any such chemicals have been used it will likely take 7-10 years for the residues to abate sufficiently for the tea to be drinkable.“