we only know Ariel was RDNA1 that is not confirmed for Oberon, meaning RDNA2 is not really a factor of authenticity here, also that cooling patent suggests high clock speeds... also very much in line with the 2GHz on Github, So I really don't see how this is of any real concern in this case.
as long as we don't have new details that aren't second hand knowledge it's hard to tell what has actually changed since the latest found tests, or how much of the chip was used.
insider infos range wildly up and down, so where should we look to and what should we ignore?
github isa point of information that we at least know is accurate, we just don't know how much it represents final hardware and what what's the full context of the tests. that's where the speculation should revolve around.
we have this data, what should we make of it?

this is the real question here