Been eating from a flaking airfryer

I’ve been cooking chicken almost daily in a cheap airfryer, it seemed a little burned but didn’t think too much of it. Today I grabbed a bit of butter to rub it in the airfryer (something I never do, normally I put a bit of oil on the chicken). The butter basically turned black with all the flakes… Now I’m panicking thinking I’ve been eating this poisonous stuff all this time? At least a year??

This is the airfryer in question: