The bug

This is the same as MC-165669 with the difference that it only works during the death animation of the mob. If you right any mob with any spawn egg during their death animation while aiming at a block through the mod, it will play the hand animation. But if you are not aiming at a block through the mob, it will not happen.

How to reproduce

1. Spawn a mob, I recomment an iron golem, since it has knockback resistance, making it easier to reproduce.
2. Hold any spawn egg in your hand
3. Look at the iron golem and make sure to aim at a block through the mob
4. /effect give @s minecraft:strength 999999 255 true
5. Kill the iron golem and immediately hold down right click
   → You will get many hand animations during the death animation