I would say searching for website addresses is a pretty common requirement as it’s a unique identifier. And yes, it is now repeatable on here. I think people would complain if searching for www.bbc.co.uk didn’t work on Google.
Maybe somebody who knows how the search engine works could comment on what Discourse is doing with the search string? Is it getting processed so that it’s not searching on what one types?
Later… and yes, having included www.bbc.co.uk in this message, Discourse is unable to find it.