I was fighting an Enderman during the day when he suddenly lost interest and teleported away. He had turned neutral and then made the stare growl sound.

This bug happens when Endermen lose hostility, so during daytime (but currently they immediately become hostile again due to MC-263303), after killing the player, or when the player switches from survival to creative mode.

To reproduce

1. Be in Survival mode
2. Summon an Enderman
3. Look at its head
   → Scary sound
4. Wait for the sound to end
5. Look at the ground and run away from the enderman (in order for the enderman to calm down)
6. The enderman becomes neutral again (note MC-263303 when testing)
   → Another scary sound

Video

Minecraft 21w18a - Singleplayer 2021-05-06 17-39-56.mp4