What are the possible causes of a changed ssh fingerprint?
Some context: after finding a sensitive vulnerability in a governmental system and disclosing it to them, something happened which I don't remember happening before. When connecting to the VPS I used to verify the vulnerability, my ssh client complained about the key; the fingerprint did not match the one saved. I verified the one saved was still there, and after immediately rebooting the VPS it matched again.
What are the chances this is due to malicious interference?