Both AMD and Google note, that Zen[1-4] are affected, but what changed about Zen5? According to the timeline, it released before Google notified AMD [1].

Is it using different keys, but same scheme (and could possibly be broken via side-channels as noted in the article)? Or perhaps AMD notices something and changed up the microcode? Some clarification on that part would be nice.

[1] https://github.com/google/security-research/security/advisor...