Crouching on the ground in a vine block treats the player as airborne

Crouching while standing on the ground next to vines causes the player to slide around like crouching on vines in the air does, even though the player is still on the ground. Mining speed is also reduced.

To reproduce:

• Place a vine on a vertical surface
• Stand on the ground in the same block as the vine
• Crouch

 

Observed Results:

The game treats the player as airborne despite them still being on the ground, reducing mining speed and horizontal motion friction.

 

Expected Results:

The player is treated as crouching on the ground.