realm is acting strange

My friends and I created a creative mode realm today we made it to the end and once defeating the ender dragon we began to experience problems. 

first of all, there is a black disk that keeps flying around our realm and it deletes blocks it flies faster than we can and it cannot be killed

things are randomly combusting and destroying our builds

we found a ravine in the world and when we returned to it it was full of shulkers and they spelled out the word HI

Endermen also keep spawning in our realm for no apparent reason

Furthermore our characters keep getting enchanted by nausea and blindness for no apparent reason making it impossible to play the game

we think that our realm may have been hacked or that there is a serious bug related to the ender in our realm