Cyrus' post was clearly meant to be in support of Styles, but in doing so, she ended using offensive language. Indeed, her use of the word "nappy" is actually pretty problematic because that term is a historically racist one — and it's even worse that she used it against Owens, a Black woman.
According to NPR, "Nappy's history is tangled up in the arrival of the first slave ships on the coastlines of the Americas in the 17th century. The likely origin of the term is the word nap, which was used to describe the frizzled threads raising from a piece of fabric. There is a lot of speculation that nap was redefined as a disparaging phrase for the coils and kinks in the hair of the African enslaved, in connection with the fields of cotton that drove the Colonial economy." In addition, Black women have been historically criticized and discriminated against as a result of their hair, making Cyrus' comment even more problematic.
In response, Cyrus posted a new Instagram story, saying "i am mortified that i used a term without knowing the context and history, but i know now and i am horrified and truly sorry" (via E! News). Hopefully this situation was just a slip up. But we're going to be watching from afar to make sure Cyrus truly learned from her mistake.