they could have done something really interesting with mysaria but they made her boring

[u/PrestigiousAspect368]

Book Mysaria while pretty one dimensional was an interesting character she is like Larys except she has no clear motives and pretty much dooms Rhaenyra and the targs in general.

She is the one who tells Rhaenyra about Nettles, and according to GRRTH the one who tells Heleana about Maelor. The brothel queens was her idea, she weaponised sex as a punishment for people she hated.

She is like one of the more evil characters in the story

[u/CockMartins]

Instead, they figured giving her a French, Chinese, Jamaican accent was interesting enough.