Brown eggs are now pale

[Eve97]

We have 2 RIR and 2 Barred Rocks that have been laying since September 2018. They were born in April of 18 and their eggs have always been perfect with the beautiful brown shell. 4 weeks ago there was been a decrease in eggs to the point of only getting 2 eggs for a week. Now the egg production has increased in the last week but we only had 1 brown egg and 7 very pale, almost white, eggs, the shells are still hard on the pale eggs. I have no idea why the color has changed as they are healthy, eating great, and always have oyster shells available, also they are drinking the same amount of water daily and I give them healthy treats. They dont seem to have any type of respiratory problems, as I have read online about infectious bronchitis, and several other diseases. If anyone can help me I would be so thankful

 

[aart]

Not an issue.
The brown coating can fade over the 'season'.
It will resume darker when birds resume laying after a molt.