I have an idea to add something like blocking the function of cooking potions at the start, i.e. you will not be able to use mana to create potions until you open the cave with slimes.
I'm saying this because I inadvertently used mana to create a potion (I didn't notice that I had already been given a ready-made mana potion to sell) and, as a result, I caught a softlock, because I hadn't opened the cave yet.