Update 2:
I believe this is a security feature, rather than a bug.
CPPC is designed hand CPU preferred core control from the UEFI/chipset to the O/S, if CPPC initializes upon boot in tandem with strict enforcement measures of SecureBoot + CSM disabled, amdppm.sys attempts to to write or read to memory areas of the BIOS restricted by the hypervisor or UEFI, triggering the crash.
Enabling CSM allows one to use SecureBoot, HVCI, IMMOU, VBS, and CI-config, by relaxing UEFI/hypervisor security restrictions.
This allows greater compatibility at the expense of security.
O/S or OS: Operating System
CPU: Central Processing Unit
BIOS: Basic Input-Output System
UEFI: Unified Extensible Firmware Interface
CSM: Compatibility Support Module
HVCI: "Hypervisor-Enforced Code Integrity" or "Hypervisor-Protected Code Integrity"
VBS: Virtualization-based Security
CPPC: Collaborative Processor Performance Control
IOMMU: Input/Output Memory Management Unit
SMM: System Management Mode
MAT: (UEFI v2.6) Memory Attributes Table
TPM: Trusted Platform Module (2.0)
