They say it’s “Platform secure boot” by AMD. They refuse to elaborate further though, and no one knows wth that is. Except AMD themselves ofc: www.amd.com/en/products/…/pro-technologies.html
Platform secure boot is designed to provide protection in response to growing firmware-level remote attacks being seen across the industry. AMD Secure Boot helps continue the chain of trust from the system BIOS to the OS Bootloader.