Kiara used to be this board's favorite to hate. It lasted months, with the frontpage full of "orange woman bad" posts. Some of it got to Kiara, and obviously affected her for a time. Especially after that one Uno collab where Kiara faced a lot of backlash for babytalking for half an hour. She addressed those complaints, as well as others on stream, and it was clear she was emotional.
But after that, she became stronger and more confident. I'm not inside her mind, so I can't say the haters never get to her now. But I feel from watching her that since weathering several storms she is even stronger now than before. Now I think haters make her laugh more than cry, especially because she knows she has so many fans backing her up. And I think seeing that was important for her; seeing that the haters were a minority, and seeing so many fans and the majority back her up and defend her. That helped her to put the hate in perspective, and make her stronger.
Right now I think something similar is happening to Mori. Mori's a different person, so she'll cope with it differently (likely through her music) but after dealing with this wave of hatred I'm sure she will come back even stronger and won't fall for the same drama/troll attempts like before.
Things are hard now, but I think the future is optimistic for Mori and Deadbeats. Defend your oshi responsibly, help both her and the haters understand that the haters are the minority, and be sure to not let the haters consume you either. At the end of the day, know you are on the winning side, unlike the haters. That's the lesson I can tell you as a KFP (and a supporter of Unity).