The Bug:

When a shulker opens one block above a player sitting in a minecart it will bump the player up and down.

Steps to Reproduce:

1. Place this structure file in .minecraft\saves\<world_name>\generated\minecraft\structures.
2. Go in that world and run:

   /setblock ~ ~ ~ structure_block{mode:"LOAD",name:"mc-104991",showboundingbox:1}
   

1. Enter the minecart and wait for the shulker to open its shell.
   → The shulker bumps the player up and down.