When launching yourself from water in a way that triggers the riptide spinning animation, the item that is not in the hand holding the trident will suddenly move to the top of the screen on it's side for the duration of the spinning animation.

How to recreate:

1. Equip a trident in main- or offhand.
2. Have an item in the hand that is not holding the trident
3. Launch from water using the riptide effect (Trigger the spinning animation)