If she's one year old then she should do her first adult molt later this year. It usually happens in early fall, but it can vary as to when it actually starts, sometimes earlier, sometimes later. I don't see any evidence of a molt just yet, you will know when you see new pinfeathers coming in. It looks like residual rooster damage to me, often when this happens they will not fill back in until they do molt. Also possible that the bare area's have attracted some picking by the remaining birds which may be why it's worsened, or you may have a dominant hen who has stepped up to fill the top pecking order spot since the roo's have gone. Molt can vary in it's severity and may be a very soft molt in which feather loss is gradual and almost not noticeable, or sometimes a hard molt where feather loss is heavy and rapid and they can be left will bare patches, or in some cases look nearly bald. There is a broad spectrum of normal. When it starts you will probably notice a lot more loose feathers in your coop and run, and a lot of feather sheath dust. Adding more protein to the diet can help them get through molt and grow feathers, feathers take a lot of protein, so switching to a flock raiser or grower feed with a higher protein content will help, or a feather fixer formula will also have more protein. Be sure to offer oyster shell free choice all the time in a separate feeder for calcium for those that need it. The non layer feeds don't have enough for laying hens, but they will take the oyster shell when they need it. I think you just need to wait for her to molt and she will fill in.
i was worried something was wrong but it seems like we just have to wait and keep an eye on her
