When we were car shopping last year, I recall Tesla listing some "new" (non-demo) inventory cars below the price of a new order of the same config. As best I could figure out they were listed at the price from when the car was built, or even from when the car was ordered (by the customer who cancelled the order / failed loan qualification / rejected the VIN / etc, leading the car to end up in inventory).
In other words, these low-priced inventory cars had their pricing assigned internally in Tesla's systems at some point prior to actually showing up in public inventory. And kept that price even when new order prices were increased. (The price increase would almost never have been after public listing, because every inventory car would get snatched up super quick back then, especially brand new non-demos.)
Per a Tesla rep back then, if we were to purchase one of these old-pricing inventory cars but ask for FSD removal (every new inventory car was listed with FSD enabled), that would reset the pricing to the current new order price. Which is exactly what happened, though it was further complicated by having the inventory car assigned to our existing order that we'd placed a few days prior at the still-current pricing. So multiple variables at play.