If you set the height of the skin created when creating the world to the maximum height, the red hitbox will appear above the white hitbox. Because of this, if the head touches the ceiling, it will take damage.
Luckily, the only way to fix this is to use /mca edit to reduce the height of the skin to some extent, then re-enter the world and the hitbox will return to normal. (The red hitbox moves back inside the white hitbox)

Version : MC 1.19.2 , MCA 7.5.5, Forge 43.2.8