How does Wandrer learn about suburbs/areas?

I've found a couple of small areas that aren't covered at "suburb" level, so travel in those regions is only applied to the city level. Example:

https://preview.redd.it/5xq5dhwjcq5h1.png?width=1787&format=png&auto=webp&s=6b282b86fd07ff8a5c90cc743e4a073f56eef331

There's nothing on OSM that shows these boundaries, therefore its coming from somewhere else.

https://www.openstreetmap.org/edit#map=17/-43.473211/172.636162

So should I be looking somewhere else to find these suburb boundaries?

Aside: Here in NZ, a suburb is not rigidly defined by specific streets or corners, like in other countries. And, as per screenshot, this is a new-ish subdivision.