Her line readings are performed in the manner of a stereotypical Hollywood portrayal of an antebellum Southern young lady - i.e. Gone With the Wind - plus the specific word choice of her dialogue in the script and the way Bailey Bass performs them are all in a manner which has a history of coded racist portrayals of Black characters in Hollywood.
Why doesn’t anyone else at this point in the show speak as if they were in a community theatre production of Gone With the Wind?
To break it down more clearly:
First, given the historical setting of the show at the point Claudia’s character is introduced, her dialogue and affect is inauthentic and inaccurate;
Second, the specific manner in which her dialogue is written and portrayed is basically your run-of-the-mill pre-1960’s token Black “mammy” character, albeit with the benefit of modern filmmaking technology, screenwriting techniques, sexual frankness and profanity; as well as over-the-top eye-rolling, physicality, facial gestures, all of which softly scream “coded stereotypical fantasy Black female character” to those with a knowledge of the history of Hollywood’s portrayals of people of color specifically Black people;
Third, I could forgive the stereotypical portrayal if the character actually Code-Switched, ie if she spoke/acted that way to seduce and kill white men I’d get it, that would work for me- but it’s how she narrates her diary and communicates/acts around Louis and Lestat - her thinking is overly simplistic (white angel/black angel), despite being 14 or whatever age she is infantilized and infantilizes herself and Louis and Lestat (Daddy Lou and Uncle Les) in an unnecessarily sexualized manner that only makes sense if she’s severely mentally ill to begin with, and given the lengths they go to show her as a mistreated/abused Black female of low socio-economic standing, her pristine and perfect handwriting - written shortly after she became a vampire, isn’t a skill that would have been plausible or probable for her character to have at that time and place in history considering everything else about her.
She’s a hypersexualized, fetishized portrayal of a lighter-skinned Black young female with the outfit, vocal inflections and mannerisms of a character straight out of a dirty manga or anime.
On top of that the showrunners have given her no room to grow and develop as a character internally (obviously she has external limitations that are essential to her character).