Minecraft's violence falls under the umbrella term "fantasy violence" meaning it's unrealistic, people and creatures don't bleed, corpses aren't left behind but instead poof out of existence after falling over, the primary enemies of the game are monsters, etc.
The "magic" nature of potions thus makes them also an element of fantasy and thus are not directly relatable to today's concepts of drugs. Minecraft's potions are not mind altering substances, they offer physically impossible buffs and debuffs and cause your body to emit colored particles.
They are performance enhancers. By analogy they have more in common with steroids than with recreational drugs.
However the above is all moot. Because potions are "magic" they are thus pretend. Children understand the concept of pretending, they are natural born MASTERS at the art. They know and understand the difference between reality and fiction. Particularly the ages recommended by the ERSB for playing Minecraft.
The ESRB sees Minecraft's current content as fit for children and adults ages 10 and up. I do not dispute their claim and see nothing that needs to be removed from Minecraft to make it more kid friendly.
Children emulate what they see, yes. But again what they emulate far more than games or TV are the people around them. They are who children pay the most attention to and thus are the ones who need most to be paying attention to those children and what those children see.