Grandpa's moonshine provides +400% melee damage, +60% stamina recovery, 100% stun resistance, +50% damage resistance, and 20 health per the code in the buffs.xml file. The picture I posted is what is listed on your character screen after drinking the item.
This isn't a bug per se, but rather a typo or 2
Also, when selecting the item in your inventory, it lists that it heals 600 health and not 20.