/sit can easily let you clip through floors and xray

This issue affects

the /sit command

How this differs from the expected behaviour

upon pressing Shift and standing back up, the player should be standing on the layer they initially issued the command from

How the issue manifests itself

by using /sit and pressing shift to stand back up, the player is placed inside the block they issued the command on. repeating this again clips them into the ground fully allowing for xray vision. it is repeatable as many times as you'd like, allowing the player to sink lower into the ground, through any number of blocks and into bases or caves without breaking blocks or movement commands.