Why is there a blue dot instead of a green dot during FaceTime on my new iPhone 16 Pro Max?

Re:" I just bought the new iPhone 16 Pro Max and sometimes when I’m FaceTiming there is a blue dot instead of a green dot in the right corner. It’s not the location service dot but more light blue. "

(Am no expert on this, yet your post deserves some reply):

May be similar to the blue and green "bubbles" in using Messages app:

You could be using cellular data if green dot, whereas when signal is strong enough, you use wi-fi = blue dot?

(Wi-fi Assist is generally on by default, and can be turned off / on: About Wi-Fi Assist - Apple Support)