I’m assuming you have the non-turbo with it being a 2018. From my understanding this issue is a manufacturing defect during the casting process of the cylinder head and not a design issue with it. Mazda has made a lot of these engines and it seems a lot don’t have this issue. My guess is that the engine will last a long time after it is fixed. The chances of having the cylinder head having the same issue is slim would be my guess.
I’m assuming you have the non-turbo with it being a 2018. From my understanding this issue is a manufacturing defect during the casting process of the cylinder head and not a design issue with it. Mazda has made a lot of these engines and it seems a lot don’t have this issue. My guess is that the engine will last a long time after it is fixed. The chances of having the cylinder head having the same issue is slim would be my guess.