I'm aware memory allocated is not memory required.Really, I would say the actual VRAM used by DOOM Eternal for modern architectures seems to be somewhere between 4GB and 6GB at 4k (and 3gb at 1080p).
I was going from here: https://www.techspot.com/review/2099-geforce-rtx-3080/
Where they see the 8GB negatively impacting the 2080. (Can't place the link at the right spot, but if you do a find for "Doom Eternal has been " you get the relevant section)
The dataset you provided seems to show a different behaviour so I'm not sure if there are settings differences that could account for that or if someone messed up something in the tests.
Still, I believe the point I made about memory requirements for max settings being expected to jump up a bit in the near future after a new console generation releases seems reasonable.
Again, if you don't keep your cards long it's a non issue, if you hang on to them, it might become one.