Last month my chickens were laying maybe one egg a week. Now, we're getting 6-8 eggs per day. No change in food, lighting, etc.
Poultry owners need to check the labels on the food bags. If the protein goes down, buy a different product. It should be noted that some manufacturers produce different poultry feed, with different mixes and different percentages of protein. I still think this rumor was started by a newbie poultry owner, that doesn't understand the entire process. Tractor Supply doesn't make feed, they just sell it from different manufacturers, yet everyone is pointing their fingers at Tractor Supply. I don't buy my feed at Tractor Supply, so I don't have a dog in this fight. But folks do need to take responsibility for being informed, check the labels, do some research, and don't believe all the crap you see on the internet.
If you have livestock and really want to be informed regarding feed, look for Feeds and Feeding, Abridged, The Essentials of the Feeding, Care, and Management of Farm Animals, Including Poultry by Frank Morrison. It's a college level textbook that goes into depth regarding nutrients needed for farming success. The book is worth your time and money.