I have a family member that has struggled to hold jobs and keep relationships, and seems to have had a learning disability their entire life, and potentially had brain damage early in childhood (due to lack of oxygen at birth, and being tasked with burning the family's trash out back (self-reported)).

I recently moved them into my house because they had nowhere to go and they are now completely obsessed with preparing elaborate dishes, growing fermented foods and carefully curating their microbiome (by doing dubious stuff they find on YouTube). This syndrome feels very much like what this family member is doing but the rarity makes me think it's probably not this.

It's to the point where their room is full of jars of nuts, fermented items, and they go into detail describing the pleasure of the textures/tastes of food and how much of a treat it is for them to enjoy random everyday things normal people eat.

My wife and I physically cringe when they talk about it in the kitchen given that they put more energy into this than seeing their own grandchildren, keeping jobs, or helping around the house.