I love that even the URL preview shows an IP address lol.
The site just grabs the viewers current IP I imagine it's probably whatever address is used by the instance to parse the URL and generate the preview, since it's different if I view it on my instance, vs if I view it on the original post on dbzer0
I assume some instance's don't have a front-end with URL previewing, but I can see it on my instance's alternate front-end (Alexandrite), and also on dbzer0's default layout.