Most birds will molt sometime during their second fall or winter and sounds just as you described in your first post and why my first question was age as it was the first suspect.
Timing and intensity can vary by individual as mentioned by the other poster. I also could not zoom in for eyes to identify anything significant. They will *usually* stop laying eggs during that time to focus their energy on regrowing feathers.
Sorry so many questions, BTW. My attention to detail can come off a bit overwhelming.
Plucked or broken feathers do not usually grow back in until the bird does molt. She should still be plenty warm enough with buddies to snuggle next to.
Leghorns are very striking and entertaining birds.