About a year or so ago, somebody in the chain of suppliers of plastic PET bottles for seltzer water, used by several different brands, switched to a recycled plastic with a distinct dark tint to it. Immediately obvious because the product, water, is obviously clear.

My family returned six cases of 15 bottles each to Costco, then found that the other brands at local stores were the same way. A couple of months later the bottles went back to normal. I still wonder if they switched back due to customer rejection of the new plastic, or if they found the new plastic was in some way leeching contaminants.