I totally left a bit off that post XD
What I meant to say was the mission server probably generates the rewards, but hasn't been updated with the new prices. Meanwhile, the "Avg Value" we see for goods as mission rewards is probably fetched by the client.
But how to solve it? Reducing mineral rewards galactic average value? Impossible. Increasing mission credit rewards to equal it? Impossible again, as missions will pay a min ~2M credits to avoid this, and the whole balancing gone... Removing minerals from rewards? Make things more complicated, a half solution. Reducing mineral amounts as reward? You will got 10 palladiums and not 39. Very bad.