Concern?

[Sono]

The yellow stuff is most likely an infection.

One of these:
https://www.merckvetmanual.com/poultry/disorders-of-the-reproductive-system

Most likely...
https://www.merckvetmanual.com/poul...eproductive-system/egg-peritonitis-in-poultry



Are you in the US?
Each state has a lab where you can get a necropsy performed to find out exactly what is going on.
I am very curious as to what you feed your flock on a daily basis.

If you feed daily treats I highly recommend stopping and only offer your birds a complete balanced diet of crumbled or pelleted type feed.

I feed them egg layers crumbles in their feeder and scratch I throw in the run, a cup full every so often. I used to give mealworms and crickets occasionally but havent in awhile now. The feed is in a bucket with the rainproof opening but is inside the coop out of the weather and only way to access it with this coop until the new coop is ready.

 

[Sono]

These are the feeds and scratch I use, depends on if my choice is out of stock , I also buy from the Feed supply here in town once in awhile which is a larger bag of the crumbles, practically identical but only if Buchheits is out of stock. I have mixed in oyster shells occasionally .

https://buchheits.com/shop/product/102286

https://buchheits.com/shop/product/102289

https://buchheits.com/shop/product/102287

https://buchheits.com/shop/product/22754