I'm having the same issue with that 2nd Fire potion (even after spamming in the city to try n find it), as well as missing two of the ??? texts (I have the Song of Pholus, but not the other two, whatever they are)
The Fire Potion is a bug I'll fix when I'm on my computer.
Unlocking each of the ??? texts are the game's final puzzle - check the insights you found and note that they're all hidden in different places.
Hi, I've fixed the fire potion bug. Thanks for informing me!