If retention samples are stored in more protective conditions, they are no longer representative of the product in the market. In the case of a complaint from the customer, how can we defend our product in the market with samples stored in better conditions than the product itself?

You have to understand what the purpose of a retained sample is. This is stated in Q7A, Section
11.7 — the packaging and holding of reserve samples is for the purpose of potential future
evaluations of the quality of the batch, not for future stability testing purposes. It’s your stability
studies that are intended to show that your material is going to remain suitable on the market.
Bear in mind, there is absolutely nothing to prevent your company from deciding that it’s your
policy to have retained samples in a trade package or in a simulated trade package. Those are
options within Q7A. That’s perfectly acceptable to do, but it’s not required. A company can
choose to use a more protective package.