Speaking as someone who has been using HMDs since '05, and periodically checks in on dynamic foveated rendering every year or so, the frustrating thing is that sensitivity to it varies significantly.

Some folks experience the image pretty much continuously and don't notice the edge blurring. Others see it every time they move their eyes left/right. This is on the same headset.

Part of it is driven by differences in eye geometry, and even color (as this impacts the effectiveness of the camera track of the eyes). I've seen the raw camera buffers for eye track on a couple headsets and they're.. a mess.

Honestly that the feature works at all, for anyone, is still mind boggling to me.