Air New Zealand made this announcement:

The ‘red’ (quarantine) flights will sit alongside the current ‘green’ (quarantine free) flights available in the booking system and will be labelled accordingly. The airline’s ‘red’ services flight numbers will start with NZ8, the ‘green’ services will start with NZ1. Please refer to the below schedule for further information.

As quarantine-free travel with Australia is paused up until the end of November, the airline still has green (quarantine-free) flights available to book from December. However, these flights will be cancelled if the quarantine-free travel pause is extended. If customers currently booked on a green flight wish to transfer their booking to a red flight, we recommend they go online to put their flight into credit and then use the credit to rebook onto a red service.