When logged out on the site, the view of any Roblox friends page (ex. Friends - Roblox)is this:
I believe this is happening because Roblox does not use the username values from the friends.roblox.com API it requests (ex. friends.roblox.com/v1/users/2865235641/followings?sortOrder=Desc&limit=18) and rather expects a redundant API called afterwards (https://apis.roblox.com/user-profile-api/v1/user/profiles/get-profiles POST) to return the username, which does not work for users not logged in and very useless either way when the listing API is doing the work.