I made a backpack material: paper and material: netherite_scrap, because I made a non-cerite backpack that does not burn, but if you put the backpacks in crafting, then they are considered as vanilla materials. see the screenshot.
Minecraft will always see it as a vanilla valid recipe when using the same recipe and materials (even tho it’s a custom model it still is netherite scrap)
I made a backpack material: paper and material: netherite_scrap, because I made a non-cerite backpack that does not burn, but if you put the backpacks in crafting, then they are considered as vanilla materials. see the screenshot.