The Mazda mechanic from the dealership even said on camera that the engine should be replaced bc if the just replace the head, it’ll do it again.
This is just nuts. This guy knows nothing except how to fleece customers. The lower engine, the short block, is not the problem. The problem is the old design cylinder heads that cannot handle the weight of the turbocharger and exhaust manifold.
The symptom of the problem is the cracked head that lets coolant leak out. #2 symptom is the damaged short block after the lack of coolant causes the engine to overheat, the head warps, and remaining coolant gets into the oil system and wipes bearings.
The solution is to put a new design cylinder head on a good short block, including yours if you haven't yet overheated to the point of getting coolant into the oil system.
The bandaid is to watch the coolant temperature. If the needle rises stop in the first, the very first, safe place. Let the engine cool. Add water. Add stop leak if you can get some. Limp home adding water as needed. Go to a dealership or independent shop and get that new design head installed.
I spoke with a salesman who formerly worked at a Mazda store. He used the words, "when, not if," the engine will break and lose the coolant. I will feel no guilt if I need to use stop leak in my engine to get to a different brand store of the same owner I bought my Mazda from and trade it in on something else. Loyalty is a two way street. If the maker and the seller are loyal to the customer, I'll be loyal to them. If not, then no. I'm still waiting for Mazda's loyalty to their customers. (I experienced Mazda's bad design when I needed expensive brake replacement and rear caliper replacement at 52,000 miles due to the calipers that did not fully release the parking brake. It was Mazda's mistake, and I paid for it. There is a technical service bulletin for these brakes, but compensation ends with the warranty.)