Hi @Richard2352
Yes, sadly Airbnb removed this functionality last year during the Summer Release. Despite many hosts requesting they return the at-a-glance feature of notes on the calendar, nothing has been done.
The only way to see a note after a date is passed now is if you added the note on an actual booking on the reservation details. Otherwise, you will not be able to go back and see a note that is not attached to a reservation on the calendar. Many Hosts have had to use a Google calendar synced to their Airbnb calendar to preserve notes. However, I have heard there are some issues with that as well.