Badges are not related to the nostr address (NIP-05):

Blue = a followed user

White = you don't follow but 1-10 of your following follows the user (hover over the icon and Iris shows the count)

Yellow = you don't follow but over 10 of your following follows the user (hover over the icon and Iris shows the count)

Nostr address is the green one between the name and the bio (in the pic sirius@iris.to).

(There was an error in the early note but the FAQ should always reflect the latest info: https://github.com/irislib/faq#color-badges-on-user-names)