Thanks for the info!!! See pics I’ve posted in original post. It just struck me odd that only one of the girls has the severity.If the other birds are picking on her to the point of open wounds - particularly around the vent - you should consider separating them if possible with a screen, chicken wire, etc so they continue to see one another, just not interact until she feathers back in.
Loosely, there are two "kinds" of molt. There's a hard molt, which may be what you describe (would like to see pictures to eliminate other potential causes), in which the bird rapidly loses, then replaces, its adult plumage. Benefits from a high protein diet while it does so, and expect laying production to either mostly, or completely, stop. Very rapid.
Or, you could have a soft molt. A few feathers here, a few feathers there. Again, high protein diets help, but they are less needed due to slower turnover of feathers. Laying production slows, but rarely stops. OTOH, it can take months to complete a soft molt and regular production to resume. VERY frustrating - I spent most of spring and part of summer this way with near a score of adult birds (many "production" breeds) offering up just 4-6 eggs daily.
and I see you've started a separate thread. Headed there next, in hopes of pictures.