@SoloSera Agree with you here, my first reaction was "What the heck?". How can the baby sister be THAT tone deaf? It isn't a good thing that you are literally throwing everything away in a single statement, including your sister. And big sister, stop being so hesitant all the time, speak your mind.
The middle frame on page 10 and the one after both look like when authors depict a character as delusional/being shocked/conspirator, like when villains explain their side, behaving/stating things to benefit you only or try to justify their actions, skin/body not being clear and her being way to happy for this situation.
Edit: Examples All of chapter 13.