This recipe requires an artifact ingredient. Unverwüstliche Herzrune der Steinform must be present in your inventory or the settlement's storage for the recipe to show up in the crafting station.
You can learn more about this from our Crafting Artifacts, Cooking Recipes and Schematics guide.
So why we gotta upgrade this if it has the same stats as the 625? pay 10k to craft and all these mats for no reason.