If you don’t have a 2.5T engine my guess is the cylinder deactivation is causing uneven wear on the heads. I’ve run into this issue with countless makes and models, it isn’t limited to Mazda. One of those features similar to stop start where you’re adding efficiency at the expense of engine longevity. Hopefully if that is in fact the issue it can be tuned out like the V4 mode on GM and dodge pickups. Best of luck dealing with mazda, hopefully the repair bill doesn’t end up solely on you
If you don’t have a 2.5T engine my guess is the cylinder deactivation is causing uneven wear on the heads. I’ve run into this issue with countless makes and models, it isn’t limited to Mazda. One of those features similar to stop start where you’re adding efficiency at the expense of engine longevity. Hopefully if that is in fact the issue it can be tuned out like the V4 mode on GM and dodge pickups. Best of luck dealing with mazda, hopefully the repair bill doesn’t end up solely on you