I think this might be new, but not positive. My iPhone 12 Pro showed a delivery date of Wednesday the 21st last night. Today when I woke up, the 21st was gone and it simply said:
Scheduled Delivery
Please check back later for scheduled delivery.
Under delivery options I have the option to modify my delivery date or time. I cannot change my delivery date to anything earlier than the 26th, but when I follow the instructions to change my delivery time (note, time, not date), it still says:
Original Delivery Window
8:30 AM - 12:00 PM, 10/21/2020
And I have the option to change the two hour window, for instance to 8:30 AM - 10:30 AM (as opposed to noon). This costs $8, so I'm not going to do it, but I wonder if doing it would increase my chances of receiving it on the 21st.