HTC, Valve, and Oculus (well before the Facebook buyout) established very early on that frame rates of 90 fps or higher with a response time of <1 ms were critical factors for preventing motion sickness. Meta either hasn’t gotten the memo or just doesn’t care.

Even with well-established VR legs, I start feeling unpleasant if my FPS starts dropping below 75 for extended periods of time.

Aside from that, it’s also down to game development. I’ve been seeing newer, inexperienced VR developers creating scenes that don’t take into consideration how our brains perceive motion; and they end up creating some nausea-inducing scenes or game mechanics, in addition to doing things like shoving your head onto the floor or through an object. The easiest example is pressing into a wall or table, and the colliders shove your head and body back when you’re not expecting it.