This also depends on the sun light incidence angle vs the view direction vector. I’d bet 100% users have this issue when exactly reproducing the same conditions I’ve posted in this topic (Santiago Chile, early morning sun about 10º above horizon in the back).
I’ve reported other problems with the shader code which are noted in the latest dev update: [BUG] Shader code 'viewdir' and shadow/light rendering are inconsistent on right eye
And the “shimmering bug” is to me clearly a combination of a bug similar to the “viewdir” one, and it is also most likely related to the “broken reflections in VR”. In effect just go outside the aircraft low on the ground with the sun behind the aircraft low on the horizon, and notice a shimmering pattern on the ground relief/details which shows as soon as you move the camera sideways, and which smoothen out and stops after a short while, but this shimmering is much less visible when moving the camera up/down instead. This to me seems to be related to the deferred reflection probing which is amortized over a series of frames and causing the shimmering on the ground during a certain number of frames and only when moving side ways.