I'm having the same issue. The server is set to Active Event so it should have the current official event (nothing). I log on, get the normal screen, but when I load my server the Easter event is activated (I can still make Easter items in the cooking pot). When I log off, I get the Easter screen.
We've gone through several events since we got our server, and they normally turn on and off with the official servers. This is the first time an event has lasted on our server over a week past the end date. I'm not sure I understand why. Are we waiting on an update from Nitrado or someone else?
We finally set the Active Event to "None" and that seemed to have turned it off. I guess we'll turn it back to "Active Event" during the next event, and hope it's fixed by then.