The culinary industry is like this, even though many things are already transparent, there are still many exclusive things that are not easily shared.
Qin Huai understands very well that Cao Guixiang teaching him without any reservations might be because she sees talent and is delighted, or maybe because Cao Guixiang herself has a good personality and is willing to teach. But it is Cao Guixiang who is willing to teach, Qin Huai is just lucky to be the student who has learned all this. The things taught by the teacher, he can learn, but he can't teach others without the teacher's permission.
There should be a basic social distance and sense between people; just because someone is good to you doesn't mean everything should be taken for granted. Qin Huai learned this from a young age at the orphanage.