Please tell me she’s just molting... we were outside all day Sunday and she didn’t look like this and I was out some yesterday and no bare skim. I ran home for lunch from work. Went out to check on everybody and she’s part naked. Doesn’t appear injured.
Assuming there's no teeth marks or other signs of a dog/predator having been up 'close and personal' an over-enthusiastic rooster seems to be the best guess.
With moulting loss is more widespread and pin feathers can be seen in the real of feather loss.
Check she's not covered with lice, too. (Fairly easily seen in the feathers and egg mats at the base of feathers and around the vent).
If it's your rooster, get a poultry saddle to protect her back.