This is a problematic item as there are multiple interfaces providing different memory clock values. Some of them respect low power states, some not.
HWiNFO is currently providing sort of legacy reporting of IGPU memory clock to preserve backwards compatibility. I could easily update this to show correct values that would also change per actual load, which would most likely differ from all other tools but that might confuse some users. So the question is whether users want to see the truth

Does the currently shown IGPU memory clock ramp up under load?
Also, what clock is shown as the main memory clock?