vaguebooking: an intentionally vague but highly personal and emotional post designed to elicit concerned responses from friends and family, often viewed as a desperate bid for attention or validation.

There is also a word "vagueposting" that defines the act as posting without enough context for the post to make sense on its own, prompting others to ask what's going on.

Another definition came from Twitter with "subtweeting". These subtweets were considered passive-aggressive, vague, attention-seeking, bitter, or anti-social.

On the contrary, vagueness is sometimes just privacy management. That's why we need to cultivate spaces online where people feel safer, and are safer.