If you apply haste lv. 2 or above to a player, you will no longer see the mining/hitting animation.
What I expected to happen was...:
the arm would swing incredibly fast
What actually happened was...:
the arm didnt swing at all and you could just see the block breaking with your arm doing nothing
Steps to Reproduce:
1. do /effect <player> 3 <duration> 2
2. break a block or hit a mob, you can see the bug better in survival