Middle school is a landmine for smart girls. There is a lot of social pressure and sticking out by being getting good grades doesn’t make you more popular.
There are a number of chance me posts on these forums from teens thinking about college and wishing they had cared more about their grades in 9th and 10th.
You can’t say nothing, but you need to be careful not to become overbearing in managing your children’s high school careers. Be clear about expecting better and why. Middle school determines whether she gets into honors track courses in high school, which may be more interesting or have more academically focused peers.