Hi,
My name is Igor, it's a pleasure for me to help others and I'll try to help you.
Microsoft says: New Windows 11 devices must use... the latest available modern device drivers based on Declarative, Componentized, Hardware Support Apps (DCH) design principles.
Basing on my experience in contacting with Microsoft developers I suppose some drivers for old CPUs are not based on these principles so some work is required from Intel, AMD, Microsoft to update old processors' drivers and these companies do not want to spend resources for this updating.
However, you may create a petition to AMD to redesign this CPU drivers.
And please note, it is possible to install Windows 11 even if a CPU is not supported. See https://support.microsoft.com/en-us/windows/ins...
Please ask other question if you have them.