I hope it is a joke (pretty good one if it is), but on an off-chance it is not: it is entirely plausible that you are the first Brave browser user to visit the site (or at least Brave of that version).
Are you sure you're looking only the "User Agent"? The text at the top is describing your entire "browser fingerprint." It includes everything the server could gather from you. Including cookies, browser version, width/height of the window, etc.
In case it's not clear, uniqueness should be seen as bad in this case. It means you can be tracked.
No idea what it means, but I am also curious. I literally just installed Brave on IOS before checking it out, so I tried it on IOS Chrome and the fingerprint was still unique.
I think it might just mean that we leak waaaay more data than most of us realize...
There's more than one iPhone, more than one IOS version and more than one version of safari. Multiply the odds of someone having your exact setup AND browsing this site.