Interrupting the Enderdragon respawn right after all the crystals are created causes the beams to shine upwards without spawning a dragon.

EDIT: Disregard this I realized this is a duplicate of MC-91748
If you shoot the end crystals used to respawn the dragon right after they create all the other crystals it freezes the dragon respawn animation done by the crystals.
Even if you leave the end and come back the effect is still there.
It goes away once you properly respawn the dragon.