In Chapter 13, why does Bri's Aunt Pooh have a problem with her song On the Come Up?

In Chapter 13, Bri's Aunt Pooh has a problem with her song On the Come Up because Bri starts rapping about violence and guns, and Pooh says that Bri is not about that kind of life. Pooh is upset that Bri is portraying herself as someone she is not.