She's been pretty flat and uninteresting ever since she came back in season three and hasn't really developed beyond what she was in her first appearance (she's selfish and depressed and wants to be free because she got trapped in a mirror... woopdy doo) despite being in the show for five seasons.
She also never really faces any consequences when she does something bad (tries to kill Steven and Connie and Greg- Steven doesn't hold anything against her and tells Greg to not be mad at her for breaking his leg, uses Jasper as a scapegoat for the Homeworld gems and Crystal Gems that trapped and used her in the mirror by forcing Jasper to stay in a fusion and taking her anger out on her for months- Steven calls Jasper terrible and doesn't listen when Lapis says she feels guilty about it, refuses to help Steven and Peridot after everything they went out of their way to do for her and stole Peridot's barn- Steven and Peridot hold no hard feelings toward her and are just sad that she's gone).
Her getting treated like a helpless wooby in every episode even though she's OP and actively chooses to do selfish or hurtful things and be a bad friend to Steven and Peridot has gotten pretty repetitive and annoying.
And I'm not really a big fan of cowardly characters, characters that have a drive, live by a moral code or philosophy, and fight for a noble cause or to achieve a personal lifelong goal are so much more interesting than characters that only care about themselves and self preservation. I also like when they have a backstory that gives them multiple layers of depth to whatever makes them heroic, tragic, or flawed, like Pearl, Rose, and Jasper's stories do. Lapis' is kind of limited to her imprisonment in the mirror and it's just meh.
I think she had potential to be a far more interesting character but they just went in the wrong direction with her, she could be worse I guess.