So, I got some new information. The OEM Brembo caliper pistons have a ceramic insert at the end of the piston. That is what is damaged, the pistons themselves should be fine. This same type insert is used in the Porsche GT3 Cup Car calipers. Probably explains why the damage looks like it shattered and disentigrated instead of cracking that you would see with metal.
This issue points at potentially a heat related. It's not a metalurgic issue as they're not metal, but possibly a maximum temperature issue.
At the same time, it could also be the pads. Maybe excessive movement of the pad under hard braking causes uneven pressure on the piston. All the pistons inserts seem to be cracked on the same side in the same area.