Ari Zucker normally has brown hair, and when she is off the show, she lets it be. When she came back, she had to go blond again, doesn't much like doing so. I think she got the bob, which I loved and thought looked terrific on her, to get rid of the dry, split ends that come from coloring at times. I had noticed she was going gradually a bit darker.
I will say it is difficult to "fix" women's hair that was short is being let to grow longer.