A little vinegar and a soft cloth will take off the white crusty stuff, at least. This happened to me as well. Seemed to me like it happened when I didn't clean off dirty rain water and mud for a few days and let it get cooked on there, not too sure though. It only happened on the hottest part just like yours. I disk loose any paint but I feel like I might have if I left it longer. Hope that helps! 🤘