Missing feathers, red butt.

[Thechickentrainer1999]

So you mean a bare spot on her abdomen below her vent, above her legs? or between?

A zoom out would help to orientate the area.

If closer to the vent, just below vent, then mating damage. If more towards the abdomen, molting? Or, yes, mite damage, or feather plucking.

If she has some bare spots on her abdomen, does she appear to have any broody symptoms? Hens will pluck feathers to make a nest.

Not sure what it is.
LofMc

I can assure you it's not from mating due since its been there before my cockerel moved in the same cage as her and she currently isn't molting as of now. I will try and get a better picture tomorrow that can hopefully help. It's right below her vent.