I get what you mean. This has been a problem for me, actually. But it's like, if the story is written from a reincarnated villain/villainess or side character POV, it's like they make the original protagonists evil? Or just trash characters. Especially the heroines, and I've gotten sick of it.
Like in this story, the og heroine was her sister, right? (maybe not heroine since this is not an 'I read the novel' Isekai, she just went back in time in her life, but the heavy implication of protagonists, side characters, and villains is there in the summary.) The heroine in the 'original story' was trash for letting her older sister work for her without feeling any remorse. But why is she the protagonist or female lead of any story? How do you even gloss over something like this?
It's happened so many times that I've begun to question who are these people writing so many books with trashy lead characters who get shown off by side/villain characters after an isekai. Even if she didn't read any kind of novel and just went back in time in her life, the summary makes it look like that kind of story. She could have just been a girl with a bad family situation who woke up back in time before her death.
Like, I don't expect everyone to be saints, but pick a story you really like (with protagonists you liked) and then picture them from the view of a side character/villain character where they're actually terrible people. It left a bad taste in my mouth after the first few times I saw it since I'm supposed to trust the protagonists in a story, if I don't then I drop it.