In a private server…?

I play on this private server from the wiki, since it’s Friday I decided to do the trick where you’re alone in a world if you go to an empty world, then go to the world you want. My main acct went to preshistoric, saw it was full and left, but I saw this and joined on my alt to see wth it was..well, that’s what it was, now my main acct is alone in a world thank GOD bc I’m not putting up with that today. The fact it’s in a private server too makes me so annoyed.