Hi efb199,
Thank you for posting in Apple Support Communities. We know how important it is to be able to see the different holidays in your Calendar on your iPhone. You mentioned that you can see if on your Mac so let's make sure it is selected as one of the calendars to show on your iPhone. You can go the Calendar app > Calendars ( should be at the bottom), do you see an options that says "Holidays in Australia" or something to that effect? If so, does it have check mark next to it? If not, you'll want to select it and see if you are now able to see the 2022 holidays.
Use iCloud calendar subscriptions
If has already been selected and you're still not seeing the information, we'll need to troubleshoot the phone itself. You can close the app out completely by following the steps here: Close an app on your iPhone or iPod touch and restart it using the steps here: Restart your iPhone.
This article contains some additional steps you can try: If your iCloud Contacts, Calendars, or Reminders won’t sync
You can also confirm that there are no updates that need to be installed by going to Settings > General > Software Updates.
Update your iPhone, iPad, or iPod touch
Hope that helps!