Just chiming in to say that this must indeed be a bug. I’m well aware that my 10700 / 32 / 3080-10 has aged but this is something else.
Spawning in Queenstown with the Cessna 208 and switching to outside view, these are my results from Windows 11 Task-manager/Performance tab + Ingame:
2020:
DX11, 3840x1600, mostly Ultra
GPU at 90%, fans spinning high
80% used dedicated VRAM + 0 GB shared
50 fps
2024:
DX12, 3840x1600, mostly Ultra (as identical to 2020 as possible)
GPU at 3%, fans spinning low
Full dedicated VRAM + 2 GB shared
15-25 fps