Hey all
I think, this may relate to the Siri Responses language/accent. Whislt the iPhone Language & Region needs to be set to US as well as Siri Request Language, you can have Siri's responses in your local accent(s).
Edit:
Someone in another forum has stated this cannot b it as there has never ben a Siri NZ Local Accent setting so they may have gotten ahead of themselves a bit with that sentence then as cannot think what else it relates to as trying to set Region, iPhone Language, or Siri Language to anything other tan US deactivates AI Siri.