I paid attention and I know where they wanted to go with Tilda (I actually have the entire Luke Cage comic series, I knew she was going to become Deadly Nightshade) but they showed her being bothered by her mom and building to the point where she needed her mom stopped but the "I want the club and now I am a villainess!" stuff came from out of nowhere.You haven't pay much attention, it was a blatant foreshadow throughout the season about Tilda and who she really was. She is Mariah's daughter it was bound to happen even when she pretended or was in denial. It was in her the whole time. What pushed her over was when Mariah kept it funky about everything to her. From that point on you saw her moving into her true self.
They should have been dropping those bits of character change all throughout as well and not just her growing realization of how awful Mariah was.