99% chance this is a mistake. Asus already corrected it.
I seriously doubt this is legit. Most likely a typo. With the RAM shortage this would make absolutely no sense for nVidia to do.
Using the 3 GB density GDDR7 chips for the slower RTX 5050 Laptop or RTX 5060 Laptop makes still less sense, than using it on the RTX 5070 Laptop. So in this regard, it's more legit.
I can't justify buying a new 8 GB VRAM GPU laptop at this point (maybe a used for 700-800), but I can a 12 GB VRAM 5060 or 5070 Laptop GPU.