Not sure if this finding is new, but the author from FASM Thread apparently has a Zen 2 (He doesn't directly mention anything besides "Ryzen 7", some other poster mentions it is a 4800HS). There were a number of articles about RDRAND being broken on Zen 2 and earlier generations but fixed via Microcode from about 6 years ago:

https://www.phoronix.com/news/AMD-Releases-Linux-Zen2-Fix

https://arstechnica.com/gadgets/2019/10/how-a-months-old-amd...

No idea what happened after. And that also means that you suddently need information about user systems BIOS/Microcode.