They've probably exhausted RWD demand backlog so I wouldn't be surprised if this was (initially)a software-limited long range battery, so that they can sell their RWD inventory.
Given that the delivery dates are 6-10 weeks in the future, they have plenty of time to put the correct size battery packs in. The previous examples of software-limited packs were in situations where they offered a bunch of sizes, more than 2, in a much lower volume product, and didn't want to produce or keep producing all of them. This time it's only 2 sizes in a higher volume product.
That would be incredibly environmentally irresponsible, considering the impact of mining lithium, cobalt, rare earths etc. You'd basically be wasting limited resources, which would run contrary to Tesla's stated mission of creating a more sustainable future.
My guess is that all the battery is used and the extra capacity allows for a "full" charge without really getting full. It could also let the range stay at the original level for a lot longer as the battery deteriorates. I would hope so anyway.