Which one specifically, there are multiple ones.
Like 3 on the top of my head.
Quinn, yeah, ok, it's in line with her character, to me she's a c..., she mentally and physically abused Riona and Mona (not sure on the physical part with Mona), sold her "Sisters/Daughters" into prostitution and deserves to be behind bars, like the rest of Buddy's and Vinnys group, but I assume that at least one of them got away and that there will be more repercussions in 12 (and probably season 4) just do add more drama for the sake of drama. I didn't really see any Character Development for Quinn (in a Neutral/Chick Run).
The "Nerds", yeah saw that one coming a mile away, they are being build up to be the big bad "Endgame" Enemy. But I still think that it was him that cheated on the test. And there is more to come with Sally in that regard i think.
The Bella Situation, yeah, that is just more Drama for the Sake of Drama. To force Conflict onto a MC/Bella run, it's a bit stale tbh.
The only Thing I am unsure about at the Moment is Jades (soon to be) ex Husband and how that Situation is going to evolve.