URL not connected to visible screen. Go into a Lab “review” mode, choose a lab entry, select view/copy, when in view mode, note that the URL is the URL of the list, not the URL of the design. Used to be different where you could save the url of the design.
I just checked an old version of the site, and this seems to be the same way it worked previously. That said, it is definitely possible to change that behavior, and I’m a proponent for seeing it happen!