Turtle helmet 'forgets' to add water breathing when not equipped on head. This does not seem to be intended as the 'glider' item tag does take effect along with any enchantment.

Steps to reproduce:

1. Run the command

   /give @s turtle_helmet[equippable={slot:'feet'}]

2. Equip the turtle helmet
3. Check if water breathing effect was given

Expected Behavior:
Player is given 10 seconds water breathing effect.

Observed Behavior:
Player is not given the water breathing effect.