Lots of effects don't work without being made specifically for single-pass stereo rendering, and planar reflections are one of them, due both the positioning of the reflection camera and the later projection of the reflected render texture. It's not too bad for most shaders, but for ray marching, reflection, projection, and pretty much anything that moves pixels around in screen-space, it's difficult or impossible to implement. The problem is, the unusual projection required for that double-wide texture needs to be built into custom shaders and image effects manually. This is nearly twice as fast - or multi-pass is twice as slow - making single-pass stereo the only real option for performance-constrained VR games, especially those on the Oculus Quest, or any PC VR that aims for a high graphical fidelity and realtime lighting. In single-pass stereo, however, the left and right eye are done at the same time, using a double wide render texture containing the image for both eyes. My scan iterval settings are defaults, i.e.: refreshInterval: 100060, scanInterval: 10006060, and I very rarely see any photos appear.
Multi-pass is the easiest and least performant of the stereo rendering modes it renders the whole scene for left eye, and then again for the right eye, so each eye renders like a normal scene. I get the following on my vanilla GooglePhotos install.
The normal method of planar reflections - with an oblique near clip plane on a second camera - works just fine for Multi-pass VR and non-VR.
