Like i said its not about 4gb of vram its that more v-ram can be used then 12, and the 12gb will bottleneck as result. If games already require 12gb it doesn't take a lot to hit a wall sooner rather then later.
https://www.tomshardware.com/video-...sis-another-game-that-can-exceed-8gb-vram-use
The 12GB cards all appear to be sufficient for 1440p very high, at least in terms of VRAM capacity, but the RTX 3080 10GB does show a drop in minimum fps relative to the 4070.
Now imagine having it RT and it will peg that 12gb of v-ram even harder.
Like i said u want to play it safe, get 12gb for 1080p, 16gb for 1440p.
All i am saying really is, that 12gb is not safe to last in the future for 1440p, better to go for more v-ram if u sit on a gpu longer.