Welcome to BYC. Where, in general, are you? Climate matters for many things.
What are the actual dimensions of the coop and run?
The Usual Guidelines
For each adult, standard-sized hen you need:
- 4 square feet in the coop (.37 square meters)
- 10 square feet in the run (.93 square meters),
- 1 linear foot of roost (.3 meters),
- 1/4 of a nest box,
- And 1 square foot (.09 square meters) of permanent, 24/7/365 ventilation, preferably located over the birds' heads when they're sitting on the roost.
8 hens
- 32 square feet in the coop. 4'x8' is approaching the limits for a non-walk-in coop even with the access door in the middle. 6'x6' should be walk-in because even the tallest chicken-keeper won't be able to reach the far wall.
- 8 feet of roost
- 80 square feet in the run. 8'x10' is a nice looking number but, remembering the common dimensions of lumber, a roomier 8'x12' is actually easier to build. 6'x14' looks good on paper but would require a lot of weird cuts.
- 8 square feet of ventilation.
- 2-3 nest boxes.
These numbers are *guidelines*, not hard-and-fast *rules* and at, under, or over them doesn't *guarantee* either trouble or being trouble-free, but even moderate crowding increases the likelihood of social problems.
I see in the photos that your run doesn't have much "clutter":
https://www.backyardchickens.com/threads/a-cluttered-run.1323792/
Clutter is important because subordinate chickens show that they accept their superiors' dominance by getting out of the way -- breaking line of sight and giving the top birds their space free and clear.
Also, how many feeding and watering stations do you have? Is it possible for a bird at one feeder/waterer to see the other feeder/waterer and thus guard the resources?
That said, as has been noted above, sometimes feather-picking is improved by switching to a higher-protein feed.