I would say things like this are starting to appear because
-Mazda prices are insane
-they are probable stopping production or already have and there is limited stock.
What needs to be done is recoating/refinishing. All my engines (I have at least 12 housings last time I counted. I thought I had 6 until I move a few boxes. Man 20 years makes stock piling!) have the dreaded corner seal triangle wear or have apex damage. Makes them useless with todays current offerings.
I'm going to drive down to Goopy Performance after my DGRR trip