Ender Dragon becomes invisible when flying to exit portal after being killed by the player

Summary:
When the Ender Dragon is killed by the player, it becomes invisible while it flies to the exit portal.

Steps to Reproduce:

1. Create a new world

2. Go to the End

3. Kill the Ender Dragon by not using the /kill command

Observed Results:
The Ender Dragon becomes invisible while it flies to the exit portal. Once it reaches the exit portal, it becomes visible again.

Expected Results:
The Ender Dragon should remain visible while it flies to the exit portal.

Video: