VEVOR Baking Steel Pizza, Square Steel Pizza Stone , 16" x 16" Steel Pizza Plate, 0.2"Thick Steel Pizza Pan, High-Performance Pizza Steel for Grill and Oven, Baking Surface for Oven Cooking and Baking

What is the tenacious oil covering the pizza baking stone and how do you get it off? I can't figure out why the stone is coated so thickly with this stuff and why it's so difficult to get off. I've been scrubbing for over a day now with various things trying to get it rid of it. Thank you