We have a full clan of ten people, and have been playing Siptah since its’ release. I can assure you there is no midnight alchemist recipe on the island. You CAN get potions of Bestial Memory from certain one-skull bosses (we’ve gotten them from Hyenas, yetis, and wolves) but they are extremely rare.
Please Devs, throw us a bone. Put the midnight alchemist recipe in the map.