system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] Why didn’t anyone at Hogwarts know that Lupin was a werewolf?

It seems like Lupin was really struggling to find work for YEARS, in spite of being a reasonably intelligent and skilled wizard which would tell me that he’s probably tried to find work at some point in some places.... Ministry of Magic, probably Hogsmeade, Diagon Alley, etc. It seems like students (thinking Malfoy as a primary case) would have known that he was a werewolf from Ministry gossip or parents who encountered Lupin in his hunt for work. Why would this not have been the case? Sure Dumbledore swore the staff to secrecy at the start of the year, but the way gossip spreads at that school, only one student would have needed to know for it to spread like wildfire.
gpt
People knew he had problems getting a job.

Werewolf would be one theory, but so would "secret addiction" or "serial philander" or "pissed off the malfoys" or countless weirder theories.

Until hard evidence came up to confirm it specifically, "he's a werewolf" is just one in a flood of rumors and speculation.