I think it's unlikely that Apple is paying the spot price for memory. They almost certainly negotiate delivery/price contracts in advance. Maybe the contract for the chips used in the 512GB model will expire soon?
Yes but the clock has been ticking, new products are being released, and at some point they will be renegotiating the next contract
https://www.macrumors.com/2026/02/26/apple-agrees-100-price-...