ok so I've just seen your update on feeding. They are hungry and are supplementing their diet with feathers from each other as they contain minerals and protein. Also probably stressed from being hungry and taking it out on each other in the coop, which seems very small. Do you only have 3 chickens?
As
@cherrynberry said, they need chicken feed ALL the time as their main diet. Foraging just supplements that.
You also need to boost their diet for a few months with extra protein because of this so they can grow new feathers. Feeding them back their own eggs (cooked) will help.
What is their weight like? Can you feel their keel (the breastbone) as quite sharp or do they have nice muscle filling it out? Are they laying regularly? They will be working really really hard to get enough to eat just foraging, and that will stop them having lots of good quality of life as they are just trying to survive.