Iris on Nostr: Blue = a followed user with NIP05 identifier. White = you don't follow but 1-10 of ...

Blue = a followed user with NIP05 identifier.
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)

https://github.com/irislib/faq/#color-badges-on-user-names