There's so many layers of compression and scaling and transforming going on that it's never going to look Great. macOS renders to 5120x2880 'display', then it'

There's so many layers of compression and scaling and transforming going on that it's never going to look Great. macOS renders to 5120x2880 'display', then it's downscaled to 4k, which is then streamed to the Vision Pro with whatever compression or bitrate, where it's scaled to whatever size you display it as.