Cooking with any plastic is a dubious enterprise, because heat encourages potentially harmful plastic compounds to migrate out of the polymers and potentially into the food. But, as Andrew Turner, a biochemist at the University of Plymouth recently told me, black plastic is particularly crucial to avoid.
In 2018, Turner published one of the earliest papers positing that black plastic products were likely regularly being made from recycled electronic waste. The clue was the plastic’s concerning levels of flame retardants. In some cases, the mix of chemicals matched the profile of those commonly found in computer and television housing, many of which are treated with flame retardants to prevent them from catching fire.
Your coating might be ok for you still, while still having lost a lot of its’ non-stickiness.
Usually, you can fry eggs on non-stick pans without butter (even if butter is delicious): can you sill do that?
It’s usually not a chemical reaction like what’s happening with acidic foods on the coating of a cast iron/carbon steel pan. Ceramics is quite brittle, so mechanical shocks can create micro cracks, which are hard to see but make food stick.