Coz that inventory lot was the cheapest Model Y with a base price of 50990 this will be given the least priority or any priority to say and most likely the last batch to be built until the demand wears out. Tesla is known to do that. I have seen earlier in the custom order page for base no options vs any added options the delivery dates range used to change significantly. Never thought they would really play this trick to get the orders with the inventory items. My understanding of the inventory item was it was already built and ready to deliver. Lesson learned.