When you jump in front of the worldborder, then the worldborder animation is jumping with the player.
What I expected to happen was...:
Nothing wrong with the worldborder animation.
What actually happened was...:
The worldborder animation jumpt with the player.
Steps to Reproduce:
1. Stand in front of the world border.
2. Then start Jumping, and look at the blue/red/green border lines.
Duplicate of MC-206805