This is a minor bug, but I basically found out that the netherite ingot doesn't have the "∫" next to it. When you enter the beacon, you see the items you can use for activating it. And each two icons have an "∫" in-between to separate them. But the netherite ingot isn't separated from the emerald. I don't know if it's a bug or a texture problem or it's just that Mojang missed it.