Im kinda with you here, if theres a v-ram shortage that is. I dont see an increase of used vram when playing tho, atleast not more then like 1 gb. The game uses ALOT tho(4k max settings with DLSS performance uses around 11-12gb). Also people with GDDR6X might wanna keep an eye on Vram temps since those suckers get VERY hot unless properly cooled. I saw temps at 90c+ before i got my backplate watercooled, now its at 60c with a hefty OC.
I havent noticed this either, seen a loss of overall fps but no degradation in fps(probably the increased RT). I get overbright for like 1 sec after closing a menu, looks like HDR reapplying pretty much but other then that it seems fine for me. Have a 3090 Oced pretty hard and this game has never been this stable for me.