I guess that pretty much confirms the theory, AMD only rolls microcode for Epyc and there is no magic sauce why the patch version are all over the place on their consumer chips. For me, the worst thing is their lack of transparency. Guess they're justification is ridiculous and incomprehensible from a customer standpoint, otherwise they would have communicated it.
Also funny that Ubuntu 22.04 doesn't ship microcode for Zen3 and higher, why don't they backport such things?