Bai Meiyue was not being alarmist; she was being practical. If not for the fact that she was more of an offensive user, she too would have hidden her abilities, but she couldn't because her skills could not be hidden.
The reason her mother was still unbothered was because Bai Meiyue had protected her very well; if not, with her abilities known to the world, Yu Miaomiao would have come after Mother Bai the first thing after getting an idea about how skilled Mother Bai was. Just like how Fox stole the soil of their greenhouse, they would have tried to kidnap Mother Bai.
Did she know about the theft? Of course she did. She had been keeping an eye on her penthouse in a similar fashion as how Yu Miaomiao was keeping an eye on her base. Thus, Bai Meiyue was very much aware of what Fox had done.
