I think you're reading something into those numbers that isn't there. Slow moving XBones does not equal shitloads of XSX/S production. In fact, we can't extrapolate anything at all about XSX/S from that.
I think you can definitely infer something from it. Xbox One has been out of stock on almost every online retailer since sometime in June, after having a very strong April and May due to covid lockdown increasing game sales. The fact that that Xbox One has been sold out for 2 months, clearly due to low stock rather than tremendously high demand, clearly means that XB1 production was stopped or slowed around about late May or June. And what reportedly started in late May? Xbox Series S and X production. It definitely seems like MS has converted most of their XB1 S production lines over to Series S now and all of their XB1 X production lines over to Series X now (XB1 X is officially discontinued).