How do you copy+paste a user handle?

There is (as far as I know) no easy way to copy a user handle to mention them in a post or comment. There isn't a UI element or menu option on a post to do this. I can go to their just page and use the share button, but then I get (for example):

https://lemmy.guide/link?target=@[email protected]

That's not Zach's instance, it's mine. To get the user handle I'd have to edit out the URL part, and change to the correct instance @[email protected].

Is that how it's supposed to work? Is the instance change thing a bug? Is there a better way I don't know about?