Iris on Nostr: Blue = a followed user White = you don't follow but 1-10 of your following follows ...

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)

https://docs.iris.to/features/users#color-badges-on-usernames