I noticed same starting about 6-8 weeks ago. I view posts via the firebase API, so I'm more likely to catch things in an intermediary state. When I view the "***" reply in the browser, the reply body is by then perfectly normal.
You guys should really ask these questions in the right place! "possible cover-up", sheesh - I know it's fun to imagine sinister goings on but wouldn't you just rather find out?
* maybe the only case - it should maybe say [delayed] but I think there might be obscure corner cases
Edit: this is fixed now... I think.
hn@ycombinator.comI assume it's because they have written something they wish they hadn't, and while they are drafting a new comment they are replacing the original comment with that placeholder.
Just my assumption, no inside info.
(The earlier flagging was obnoxious, but your over-the-top accusatory style will certainly garner flags, as well)
You can see flagged posts by enabling showdead=yes in your profile. It's not deleted. It's good that you as second person saw the "**" posts and thanks for adding more detail. Might indeed be something with firebase API. The mystery won't be solved by second guessing the cause though. Best way forward is if you email the moderators (link in footer) and provide examples to further debug.