This was all widely reported several years ago and I have no idea if anything was ever done about it, but:
Amazon were notorious for not having proper control of their stock. Marketplace sellers supply goods to the amazon warehouses where amazon just dumped all identical product sold on behalf of and supplied to them by different sellers, into one uncontrolled batch. You the consumer buy a litre of D4 from marketplace seller A and you might be sent a litre of D4 that marketplace seller B had bought short dated on the cheap and consigned to Amazon where it got mixed in with the D4 sent to warehouse by everyone else.
Nightmare for the consumer as you can't learn which sellers have good product.
Nightmare for the dilligent sellers because they get blamed for substandard product sourced by other sellers.
Of course looser stock control is easier and cheaper to manage for Amazon. Amazon marketplace sellers affected are the little guys who are ten a penny to amazon and can just be ignored :-(
So if this came from someone's shop on Amazon, don't assume the worst about your vendor, they may need it as proof in case Amazon is still up to their old tricks.