When using D3D12 with foveated rendering there is a discrepancy between multipass and single pass instanced.  SPI seems to be using the same eye for the foveated shading for both eyes.

This seems most evident when using the mock HMD's option for "eye independent" gaze simulation.  both eyes move the same which differs from MP where they move separately.

There also are differences when using asymetrical eye shading as well where one eye seems flipped between the two rendering modes.

Attached a zip with MP and SPI D3D12 asymetrical shading to demonstrate.

Repro:

You will need to use the foveated-rendering/d3d-vulkan-settings-asymmetric-ratios or foveated-rendering/d3d-vulkan-settings branch of the mock hmd repository (https://github.cds.internal.unity3d.com/unity/xr.sdk.mock-hmd).  You will need to pull the branch and then build the mock using bee.

Add the mock hmd to project and in the player settings choose D3D12 and in the mock settings enable foveated rendering and independent eye movement for gaze simulation.

make sure you have a PC with a 2080 or better and recent drivers (like within 2022)

build and run using single pass instanced and multipass.

results:

mp and spi are rendering foveation differently

they should look almost the same instead