Breaking a block triggers the attack cooldown server side, but does not trigger it client side causing a desynchronisation.
As a result the attack indicator indicates that the player is able to hit a full charged attack when he isn't.

Step to reproduce:
1. Create a world, get torches
2. Summon a NoAI mob
3. Go in survival, place a torch
4. Get an axe or sword
5. Break the torch then quickly hit the mob
The attack indicator shows the cross for full charged attack but the attack performed on the mob is a weak attack (no sweep for instance with swords)