Lights Flashing in Left Eye (Unity 2019, Quest)

Some questions to get a better idea of whats going on:
-forward or defered rendering?
-type of light, point, directional etc..
-single or multi pass rendering?
-are you using any custom shaders on the materials affected by the lights?
-how many lights?
-are you able to test in editor and if so do you see this happening under those conditions?
-can you better describe when the flicker happens? Ex: does it happen when you move/orient the hmd?

Thanks MikeF.
Here are the further details:
Forward Rendering.
Mostly point lights.
Single Pass.
No custom shaders.
Lots of lights (50+).
Does not happen in the Editor at all.
It happens while the HMD is in motion and still - but only on the left eye.
It appears (in testing just now) that it only happens on a flat surface like a terrain (however it does this on flat surfaces other than a terrain (like a plane).  It is not flashing at all in the left eye for other surfaces.

First thing id try is to remove the terrain and see if its still happening, ive seen lots of weird lighting issues with terrain over the years and adding in mobile + quest variables to that mix sounds like trouble.

Next id try reducing the amount of lights in the scene. Generally speaking you dont want any realtime or mixed lights on quest, but if you need to i think oculus recomends no more than 3 point lights (that might be old dev kit docs though, cant be 100% sure on current recomendations).

The fact that its happening in one eye only is odd, but given the two points ive mentioned above potentially causing a number of problems i wouldnt doubt other side effects like this could present themselves

Yup.  I tried getting rid of the terrain first thing - does it still if there's just a flat plane as well.  I'll try marking all the lights as Baked and see if that tightens things up.  Thanks for the suggestions; I'll report in on what I found.