This is the issue they're certainly talking about: https://www.phoronix.com/scan.php?page=news_item&px=Ryzen-Se...
And it is assuredly not a problem with any Ryzen processors manufactured after the very first few months.
After applying workarounds, I still see some strange crashes, not sure if at least some of those are still related to the CPU hangs from the bug above. TBF this might not be the CPU's fault. This is all quite annoying to me and time intensive to investigate (where do I even start?). Even though I really like AMD's tech I am quite frustrated and I haven't had these problems with my previous Intel builds so far...
I never experienced it myself but in my BIOS there's an option about "power on idle" that's suggested to not turn off for compatibility (I don't recall the correct words but I could check).
It usually depends on MB manufacturers and BIOS/AGESA versions.