From the Metal (API) article on Wikipedia:
"Metal 3 introduces MetalFX upscaling framework which renders complex scenes in less time per frame with high-performance upscaling and anti-aliasing."
For anyone gaming in Ventura or working in 3D, it's best to use a Metal 3 compatible GPU.
Metal 2 GPUs will still work, Metal 3 support is good to have but isn't a requirement for Ventura. RX 400/500 series cards work with no issues. They just lack MetalFX upscaling. I've used a Radeon Pro WX-2100 and an RX 570 with no problems to report. Even UHD630 graphics have Metal 3 support so there are many options for Ventura.