Hi @redonihunter,
Answering your question:
"Where is this?"
Every time someone makes a comment, the username is displayed, I don't see how enabling access to the usernames can make it too much worse.
About what you mentioned:
I think you are saying that if the user never interacts in the platform, they don't have the username exposed, right? But I am not sure if I agree that exposing those could be a security concern.
You mentioned the usernames are accessible via cookies, if the apps can access that information I think this is even more concerning in terms of security, right? Also, cookies can be manipulated so you cannot rely on the information there, users can potentially modify any content there.
And finally, you mentioned that itch.io is not "this type of social network", I disagree. Yes, itch.io don't have all the features other social networks have but I think is implicit that any interaction you have will expose your username. Like creating a comment on this post, creating a devlog or publishing a game.
Itch.io doesn't have any authentication so there is no way around it. I would like to have this feature, I think it can be really useful not only for high scores but to learn more about the players.