Hi, welcome to BYC!
Probably from preening.. even by a flockmate next to her on roost, since it's only one side?? Or maybe she's rubbing the wall or other barrier going in and out of the coop, etc??
Feathers won't improve until they are molted out and replaced. They can get a bit ragged looking in the later part before their first molt, just from standard wear and tear..
Get a good check below her vent and on her abdomen to see if the skin is light and fresh or angry red to help rule in or out the possibility of exteral parasites. After dark using a flashlight or headlamp and parting feathers down to the skin to look for things running away from the light will give the best and easiest picture.
Higher volume layers will show feather quality issues sooner than lower volume layers.. as laying is highly taxing to the system. It can be
one way to discern laying volume in a bunch of birds that all look the same.
Side note.. if you're not already using a flock raiser or grower with 18-20% protein and oyster shell on the side free choice.. will give the best outcome for molting, feather quality, and also immune system support.. as opposed to 16% protein layer feed. It's the amino acids that make the difference.
What little I can see in those pics.. overall she looks lovely and otherwise healthy!