Console/controller issue

I must say, really, really weird. Try
power cycle your console.

Try remove and then add her account again after that. Are you sure that you didn't changed something with controller on her account?

After having controller issues myself over the years, I wouldn't think that it was the console. If after going through the link that I originally included you don't notice a difference, you could try another controller if you have one. If the same issue
happens with that controller you could see about getting your console serviced.

I would remove her account and add it again just to see if that changes anything? Are you sure she didn't change any of the settings in the game that she is playing? Sometimes if you increase the sensitivity of the camera in a game, it might seem that
there is controller drifting.

This is not a console problem. It is the controller drifting. There could but something broken inside the controller or dust. If you still have warranty then I would recommend getting a replacement. You can do that here.

But what if its the system not the controller