Well, I just introduced the new 6. These are the older 6 that had these issues with just them. It didn’t start once I had all 12. It was like that for over a year with just 6 of them
Treat for mites then and I would switch to a higher protein feed to help with molting since it has been going on for a while. 18% protein minimum with 20% protein ideally. Chick starter/grower has 18% and all flock has 20%. Make sure you have oyster shells on the side when doing that.