Currently in Minecraft 1.14 Slimes attack in very quick succession. This allows them to be able to break shields within seconds. I have tested if this was also the case with armour, it does, but the slime will only take 2-3 durability off within one strike.
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gaspoweredpick
violine1101
To me this rather sounds like server lag. Did the slime stand still, and then attacked you unnaturally fast?
NeunEinser
Resolved as dupe of MC-169167, since that one seems to have the required information.
migrated
I think this is a problem with the shield, not the slime. If a hacker punches with auto click on a blocking player fast enough, it will destroy the shield instantly. This is caused by the shield being able to take damage with absolutely no cooldown, and it can glitch the way the shield takes durability damage and make it take durability damage despite doing what should be 0.2 damage. Try blocking multiple pufferfishes at the same time on normal difficulty, they will demolish your shield despite the expected result that they shouldn't damage the shield at all as they do only one heart of damage.