1)
Nope, see here on my IGN video 9GB Vram and 15.5GB System ram used. Now watch as the SYSRAM drops back down to 12GB, nothing else running on my machine at time (Aside Windows munching 6-8GB) meaning at this point with RT off at 4K total Ram usage here was a minimum of 11+GB. likely into the 12-13. Creating pages, temp data to work with is common fault. This is so heavy who is to say they do not have full logging running on all versions and this is the cause. As I keep stating, the code is the issue not the hardware but right now I have showed you twice the receipts that is proven.
3) Yes we can, it is known, if you write code and work with data you know this, we do not need to get access to the source or diags to prove this fact, it is a known fact. What and how much the issue is here is the unknown, but I never said otherwise.
4) Again proving my point, and this is just one spec and API, all these and much more become a factor and can present differently across each. The SX and PS5 code are not the same even from Xbox and PS4 let alone PC, AMD, NVIDIA, INTEL etc.