Playing the experimental patch.
I notice once I passed mid game no food vendor sell Pickled Mindshrooms and Psi Beetle Brain Soup. I know this is not bad RNG because I've been doing merchant runs and even used speed hack and can confirm they are no longer for sale.
My char is currently holding 4 Pickled Mindshrooms and 7 Psi Beetle Brain Soup, been hoarding them like I do with potions on Skyrim -_-.
I'm guessing it's either:
1) a trigger for npc to stop selling them after a certain point, or
2) a global limit and how many of them are for sale
Please correct me if I'm wrong in my assumptions. However if this is intended behavior I'm guessing you don't want player to circumvent the increased psi cost by using high level gears + Psi Beetle Brain Soup. I'm fine with that but I don't think Pickled Mindshrooms should get this same treatment as it only increase the psi critical damage bonus. Psychosis already got hit hard as it is and I don't think this is justified.