So, Yifu says he prices Batch2/Batch3 and chips not according to their manufacturing cost, but based on profitability calculated by estimated difficulty. And that's why he is offering a refund to Batch3 because the shipment has been delayed and the difficulty has risen significantly.

So if the prices are based on difficulty, why doesn't the chips price go down every day/week? He should keep reducing the prices for new chip orders based on the increasing difficulty!