This video is rendered at true 120 FPS. Therefore, the maximum resolution is 5K/2880p. As it turns out, not a single modern VR headset is capable of properly playing true 120 FPS in 8K VR.
If the video stutters, try downloading it in maximum quality instead of streaming it. Restarting the headset or using different players may also help. Tested on Quest 3 + 4XVR.