The profile does show all the things it should, including the "verified App" and the "Supports Commands" badges; it definitely is the real thing.

But also, see all the other comments here for why doing this doesn't really matter anyways.

That's because Discord doesn't send you data for a "random user" without you having permission to view it. So, if you mention them, it will show `@unknown-user`. For me, the user was fetched as soon as I actually banned them with /ban, since there's now a relationship between my server and them.