first ender dragon passed through end portal, fell through bedrock at spawn chuncks breaking my world (broke mob AI, chunks dont load, some physics affected)

I entered the end portal for the first time to fight the dragon. I was fighing it when the dragon suppenly dissapeared and i noticed that the end portal was now lit. I looked for him and found him in the spawn chunks in the overworld. I tried to kill him but hes just flew down into bedrock and everything stopped working. All the mobs stopped moving and taking damage, my world stopped loading chunks and my character could breath underwater. The dragon i still under my world and i cant do anything in my world nor can anyother player join it