Odd shadow appears underneath the player when he is falling while inside a boat

Summary:

When a player gets on a boat and starts falling, an odd shadow will appears between the character and the boat, following the player untill land on the floor

Steps to Reproduce: 

1. Place a block in the sky
2. Place a boat above the block
3. Get on the boat
4. Start falling in the boat

Observed Results:

As long as you can see, a shadow will appear in the boat, glitching, appearing and disappearing frequently, probably being the player's shadow, that was not supposed to exist in this situation, since the player is not far from it

Expected Results:

The shadow should not exist

Notes:

Screenshots/Videos Attached: Yes