
i think this could be something with etiquette...i remember reading several historical stories, where it wasnot allowed for an unmarried women to tie her hair up. or in general for someone who did not yet have her coming of age etc. it has something to do with showing who is an adult and stuff...but here i guess it is some kind of grey zone. because she is still considered underage, but is already married and considered a step mother....so guess she is a special case...and in the beginning she mentioned how in her past life she excessively tried to look like an adult in her child body and made a laughing stock out of herself for it and that now she is going to act age appropriate so she can gain the merits of someone who is still a kid...like sympathy etc.

I actually think it is meant to be symbolism for Shuri's being and an aspect of her character. If you pay close attention to the way she dresses herself compared to other women, you'll notice that while Shuri wears good quality clothing, all her clothes are very minimalistic: no flash and flare, no lace, no jewels. Given she is the Marchioness of the richest noble family in the empire, it is not that she cannot afford them. Rather, Shuri possesses a different mindset than the other noble women surrounding her regarding what is valuable in life. In addition, Shuli has a position of power opposed to other noble women whose power comes from objective beauty. As Lucretia notes: "all I can do is sit and smile like a soulless doll".
Also, (depending on the culture) lose hair is considered symbolism in regards to freedom, innocence, and purity in character.
So I'm really curious about one thing. All the noble women keep their hair tied up, that's like a social rule. But why is Shuri always shown with her hair down? Is there some meaning to it?