Size difference between Prores 422 HQ and NRAW

Good morning fellow redditors,

I've started to dabble in videography using my trusty Nikon z6iii and I've stumbled upon something weird.

Right off the bat I would expect ProRes 422 HQ to be lighter than NRAW on high settings, but in practice it doesn't seem to be the case at all.

Using 4K@25fps, with a 1Tb card, the z6iii estimates a total of 2.5 hours of footage for Prores 422, but NRAW seems to pump this number up to a whopping 3 hours.

Any idea as to what is happening here? Why does NRAW seem to be lighter when it should theoretically yield much more information? Am I missing something?