I noticed a bit of venom in her voice when she told Gold that Regina had locked her up. I suspect that Belle is not the same person she was before she was imprisoned. I would imagine that being unjustly locked up for at least 28 years (plus however long she was imprisoned in FTL before the curse) would change a person. And while I don’t think she has transformed into evil Belle, she is in the perfect position to become the axis of righteous rage (similar to the Count of Monte Cristo) in the storyline.
I think her imprisonment will make her more willing to let Rumple do what he must (ie: use magic) to find Bae. I too heard that venom in her voice when she told him about Regina and being locked up. I think we can contrast that to when she remembers who she is and tells Rumple that she loves him. Even after being turned out of his castle, being told that she was less important than his power, and being his servant, she still loves him and those are her first words to him after “waking up”.