EnderDragon will land very rarely during Fight, often flying in circles, and regenerates to full health and teleports somewhere above the portal when relogging.

The EnderDragon during the fight will just straight up refuse to land and will fly in circles after all crystals are destroyed. Relogging causes the dragon to fully regenerate and teleport somewhere above the portal. After it lands once it will go back to refusing to land. I'm actually completely stuck in the end because of this because the dragon will also refuse to land after it is dead, not allowing the fight to end.