well when there are 2 APUs appearing, both from AMD, both very much console like and one of them is clearly linked to sony, there isn't much left to link the other one to
also the github leak didn't technically have a TF number for the Series X, 12TF was just a speculation based on typical clock speeds (1.7ghz)
the Oberon tests had clock speeds attached which is why we had that 9.2TF figure
and also, I could easily see early dev kits for both using RDNA1 chips, so it's hard to rule out insider info based on that. especially since RDNA2 doesn't seem to be a super huge improvement over RDNA1.
because again, features like RayTracing and VRS are not really part of RDNA2, they are part of their roadmap and many RDNA2 PC cards will have these features, but I would not be surprised if AMD releases low end or mid range RDNA2 cards with no RayTracing hardware, just like Nvidia sells their GTX1660, which just like their RTX20 raytracing cards uses their newest architecture (Turing) but has none of its new more notable features like raytracing or tensor cores.
if you see their Raytracing hardware as a separate piece, which it essentially will be most likely, then what RDNA2 really is is just a more efficiently running version of RDNA1
so using early RDNA1 approximations of their target specs for early dev kits is a highly likely scenario... there have been weirder early dev kits for game consoles like the Apple Mac PCs used as early Xbox 360 dev kits