The Bug:

When a villager is on the water with a kelp below it's feet, the villager will spin and unable to get out of water.

How to reproduce?

1. Dig a 2*2*2 hole.

2. Change the bottom of the hole into blocks that can plant kelp.

3. Fill the hole with water.

4. Plant the kelp until it reaches water surface.

5. Put a villager in the hole.