The bug

When a solid entity such as a shulker or boat get levitation, when the player steps on it, they will fall through the uprising entity, through that they will also be pushed aside when falling down.

How to reproduce

This experiment was created with the following command:

/summon minecraft:zombie ~ ~ ~ {Passengers:[{id:"minecraft:shulker",NoAI:1b}],active_effects:[{duration:-1,amplifier:1b,id:"minecraft:levitation"}]}