As Matt noted, it seems to be a function of Discourse itself, though we’re not sure what their intention is. (In addition to the cloaked-post class being added, the entire article element is removed from the DOM )
FWIW, I’m able to reproduce this on iOS and regular old Firefox on macOS if I make my browser window short enough 😵💫
But anyway, to answer your question! To my knowledge there aren’t any other posts on that thread, only the top-level post announcing the release:
So the cloaking seems to be how they handle infinite scrolling. They remove the content to save RAM and rendering.
The issue is that in this case they wrongly assume the post can be hidden/removed.
That could be related to the hidden post that you can see in the DOM. They seem to be related to the special status of the thread (pinned globally, listed). You can even sometimes so the post count at the bottom of the thread.