The current behavior (I’m using the web client) as it is displays self-post as (kbin.social) under the thread title. Not sure if it is the result of a fallback behavior.

On mobile it gets really awkward because the URL address bar would truncate to the domain + TLD (the full URL is only down once the user double press the address bar which makes it cumbersome and adds an extra layer of step) and for certain topics such as metatalk the user viewing the thread would have a higher chance of confounding it kbin metatalk instead of maybe lemmy.world meta talk, etc.