I think it is that simple. Maomao (and her adoptive and biological fathers by extension) were outclassed by Suirei. That means that there is someone out there with better knowledge of medicines and poisons and Maomao is now aware of them. It's either Suirei herself acting alone or Suirei's masters. Maomao wants to rip every ounce of knowledge out of them once she find them.
It's not something mythical. Suirei used it on herself to escape.
Maomao will not let stand the existence of someone who knows how to formulate something that lets you fake your own death and then "revive". She wants to learn the recipe from them before they get caught and killed. Nothing more or less than that. Maomao has remarkably straightforward ambitions, primarily the pursuit of knowledge.
Maomao knows part of the recipe is morning glories because Suirei told her, but she doesn't know the other ingredients, the proportions, or the proper administration of it to get the intended effect without killing yourself. Not knowing about something this fascinating is not a state that Maomao can tolerate.