Grim tools says that it’s from Ashes of malmouth, does this mean that the recipe only drops in Ashes of malmouth content?
No, it just means that it was added to the game in that expansion; it can drop anywhere.
Btw are you farming the Mythical one or the 75-level one?
Nope, I was farming the mythical one. But I found it. Thank you @medea_fleecestealer for the clarification