Created attachment 434511 [details]
Example of selected link element
If you right click any link it will highlight/select the link element/text.
It's rather uncanny especially for large elements.
Created attachment 434512 [details]
Example of selected link text
Note that this is consistent with what happens elsewhere on macOS, though I'm unaware of any large hit-boxes like the large element screenshot above.
The large one is coming from here: https://www.heise.de/ (german IT news website)
Also where in macOS does it actually do that? I've never seen it anywhere.(other browsers don't do it as well)
Sam is correct, selecting the text (or link) that corresponds to the context menu is expected behavior. WebKit supports other behaviors for other platforms (see bug 23351 and related).
Now whether the selection at this particular website has to be expanded all the way out may be worth a deeper look.