Discourse has this feature for “self-moderating” communities, where flags combine together, with some weird scoring maths. When the score gets above a certain threshold, Discourse assumes the flags are correct, and hides the post, while also sending it to a moderation queue. Later the moderators can decide if the flag is upheld, or removed.
Now, I said hides the post. Posts can be the initial post of a topic, or replies to a topic. When flags are made on the initial post, the post itself gets unlisted.
I am not a moderator. I have no further information. I suspect that this is what has happened here.
Some refs here: