No, like with a cast iron skillet, the hard, black, very-attached, coating is the burnt oil. Cast iron and carbon steel are normally shiny metal, not dull black, without this layer.

The oil fills the pores of the metal and polymerizes. Subsequent layers cross-link with each other to develop the non-stick coating. It doesn't really 'come off' although I'm sure small amounts will occasionally. It doesn't contribute to flavor and it's not exactly toxic. Same deal as cast iron, details here. [1]

[1] https://www.lodgecastiron.com/cleaning-and-care/cast-iron/sc...