Self-mocking type of videos on clubs social media have been pretty popular for a while. Zenit have already been mentioned, here's an example
from Roma, San Marino does it on twitter to an extent, smaller clubs also do it. There's a small dutch club who's closing on the top clubs in terms of followers due to only doing humour posts, poking fun at
Man City among others. So I wouldn't think there's hacking or rogue admins involved. Just a mishap from a failed attempt at going for self-deprecating humour. Like when someone at a party that kills the room with a bad joke type of thing.