I received the Meta Academia’s only Announcer badge for linking this question. If I am not very much mistaken, the only place where I shared this question was this comment on a popular question. According to this answer I should not be able to receive the Announcer badge for this, as I only shared the link within the SE network.
Assuming that nobody else shared my link as it is, this is an unintended behaviour. Given that this has not happened to me with other cross-site links before, in particular the one in this comment on another popular question, I guess that the combination of a link to a per-site meta and users without an account on Academia clicking the link is responsible for this. For the same reason, I also assume that this might be a different issue from missing
REFERRER headers, as already described here.