As far as we know, Baiyao has not applied for a patent. Patents have a term of protection. Invention patents usually have a protection period of 20 years, after which they will be made public. In other words, the state will give the patentee the exclusive right for 20 years, but in order to make the patented technology play its greatest role, it will eventually be announced.
Considering the time limit of patent, some technologies exist in the form of ancestral secret recipes, so that they can never be made public. But at the same time, there will be another problem, that is, after the formula is cracked by others, others can apply for a patent.