I'm working on a 3D image/video solution so I'm using the 'per eye camera' option in the OVR Camera Rig in Unity. I noticed that if I toggle this setting on and off, the scale of the world is radically affected. With the per eye camera setting off, the eye separation appears correct, but when I switch it on, it seems to jump. I don't seem to have any control over this and so it is completely breaking my project. I'm using Unity 2019.3.2.f1 on OVR 1.42.0. This issue occurs when using Oculus Link on the quest from the editor and also in the Quest build.
I've done some more digging and it looks like the eye separation is in line with the user setting on the headset. I'm now suspecting the FOV as a possible source. I tried a completely separate project and found the same issue (toggling the per eye camera setting in the OVR Camera Rig changes the perception of scale). I noticed that the hand tracking is correctly aligned with my real-world hand when using the single camera, but when per eye cameras are enabled, my real-world hand moved much further than my virtual hand.
Ran into the same issue with XR on Oculus Quest (Unity 2020.3.26f1) and setting the TrackedPoseDriver for the LeftEyeAnchor and RightEyeAnchor to use Input Actions 'centerEyePosition' and 'centerEyeRotation' solved this.