It isn't only because she shows up them. But it is also just how she does it without seemingly any real care and exudes an aura of ''If I could do this, then why can't you?'' that really gets on peoples nerves. She is also 100% always serious and all business like which makes it hard to approach and learn that she is actually a very caring and kind person. Basically she doesn't only have a resting bitch face, she also has a resting bitch aura despite how nice she is. Or a nicer more noble way to put: She has impeccable ettitquete but not the social grace to apply it properly.
To Serina avoiding the game's bad ending for her Lady is giving her happiness because it isn't the worst case scenario, but she never considered if that would lead to Amelia being happy about it. We don't know how exactly she was portrayed in the game but since it was the PoV of the Heroine and not Amelia it probably would not show her in a very good light. It probably never went into that Amelia is just a super serious and strict person who actually only wants to marry the prince out of a sense of duty rather than actual love and she only reprimanded the heroine in the most technically correct way she could.
See the thing about that is back in chapter one Serina is explicitly told by other maids that being Alemlia's personal maid is the hardest position and that she has a terrible personality. People don't hate and fear her because she's successful. They hate her because she "lacks" the ability to understand that her strict code can come of as uncaring. Almelia is a very awkward girl who is extremely easy to misread as cruel when she just wants to come off as a stoic authority.
We know that the hierarchy of nobility in this country is strongly tied to magical power, so it shouldn't come as a surprise that the crown prince will feel threatened by someone stronger than them. They're a direct threat to his future authority.
Almelia was an antagonist in the game, so there's no guarantee that her personal circumstances were all that well fleshed out. At best she'd get the warped perspectives from the prince and from Almelia's older brother since they seem to be capture targets, but we can tell that neither of them really understand her.
her brother didnt dislike cause shes better, or at least wording it like that makes him seem way worse. he experienced her being very strict and berating with etiquette and stuff and because shes really good at these things (even when they were young) he couldnt say anything against her, so he started fearing her. which id say is different to disliking someone
Aside from what toapat and DarkeLourd said, chapter 4 and 5 also show some glimpses of Serina's low self-esteem
You're not wrong but after chapter 5 it's hard to not sympathize with Almelia about that, haha
