In Yop Poll > All Polls I see a column "Author" in the listing table (also present in the Templates listing table). This column reveals the username of the one created the poll/template. It should be using the Display Name instead to avoid potential security risks when there are many users in the site (e.g. Authors can see usernames of Admins if the latter have created some polls).
That's why we have Display Name in the first place, to display it publicly when needed. Except where username is explicitly required, it shouldn't be listed.