maybe they "transfered" the magic she was supposed to have to her "older brother", for the reason being as to why she can't use magic?
I agree with them sealing it but I also think trauma, being told she is incapable to the point of believing, and the constant inability to protect herself is another major reason she can’t use magic.
Yeah totally agree with this. I actually wanted to put this in my original comment but decided against it because many times trauma is the reason their power unlocks. According to the manga and manhwas
I have a theory that she can’t use magic rn because the people who “took care of her” before sealed her magic or something idk. It’s just a theory