Where do they mention VRAM ? They only say RAM on the slide.
I'd say there is 8GB of HBM2 for the GPU and 8GB of DDR4 for the CPU.
ArsTechnica blurb used VRAM but it wasnt the actual slide or a typical stats listing, just a paragraph around it so maybe its their interpretation of it.
After the event, Google provided a fact sheet to Ars Technica confirming more stats about the hardware included in the Google Stadia stacks. These include custom-built AMD GPUS with 56 compute units and integrated HBM2 memory; "custom, hyperthreaded x86" CPUs (no manufacturer listed) that run at 2.7GHz "with AVX2 SIMD"; and "a total of 16GB combined VRAM and system RAM clocked at "up to 484 GB/s."