Comments of chapter undefined of Transmigrating from a zombie world to become the mecha kings wife

I wonder if Su Scarlet/Su Yan was originally the same person. I remember the parents and older siblings said Scarlet was( normal) a smart and caring and creative person before, then something happened and she turned ( abnormal) greedy,manic episode( bipolar),I'm wondering if Scarlet died, when to modern earth and faced the apocalypse, while another soul took her place, thus causing the abnormal reactions, now she returned backed to her body.or she was always Scarlet, died, went to earth to train and return to her body