The damage animation is played (both in first-person and in third-person) when the health boost effect is removed in creative or spectator mode

Do also note that this happens in survival as well. I did not count it as you are actually losing health in survival, but thought I'd mention it in case I'm wrong

Steps to reproduce:

1. Run this command in creative mode: /effect give @p minecraft:health_boost 1
2. Notice when the effect runs out the damage animation is played

Expected behavior:

Nothing would happen because the player is in creative/spectator mode