It differs on a case-by-case basis. A chicken will only eat as much protein as it needs to sustain its energy levels, so it will never eat too much protein. But protein percentages in feed are formulated to account for this to make sure the chicken gets enough nutrients for the amount of feed...
Do you know when the feed was milled? Most commercial chicken feed is stored in a central warehouse for what could be many many months before being sold to the customer. Nutrients and amino acids deteriorate VERY quickly over time so fresh feed is crucial.
If you just have layers, 22% protein...