Not as in physically leftover chips. The rumour is that Microsoft or some other company but probably Microsoft we’re looking at making a gaming phone or something so they needed a powerful APU that was power efficient and didn’t generate a lot of heat. So AMD went through the whole designing process with them only for Microsoft to decide at the last minute to pull out.

Very few chips wherever actually made, but Intel still had to eat to the cost of the design process, so they were casting around looking for someone who wanted the chips so they could make their money back. Somehow Valve found out about this said to AMD that if they turned it into a CPU (because they wanted a laptop GPU not a mobile GPU) and made some other tweaks, they’d put in an order for tens of thousands. So that’s what AMD did. It’s unclear if they got a deal on the GPUs or not, whether or not they did will have a big impact on pricing.

If this is true then this would have all happened around 2021 so the run will be basically complete now, but valve can still putting orders for more if pre-orders exceed expected values.