VR PC Deferred DX12 SM6 - I need some clarification

Unreal Version 5.5.4
GPU: 2x Nvidia A6000

I am developing for VR PC.
My goal: To use Lumen for GI and Reflections.

Current Problems:

  • When using DX12 and SM6 I am getting a “mirage” effect.
  • FPS is too low.

I am forced to switch to use SM5 and for better performance using DX11.
When doing so, I wonder what GI & Reflection Solution will be used.

When using a PPV and I am changing the GI Solution from Lumen to None.
It’s the exact same - no difference.

I am guessing Lumen needs DX12 and SM6.

But when switching to DX11 and SM5 → what GI solution is UE5 using at this point?

Besides, I don’t understand why DX11 and SM5 is deprecated, when it seems currently impossible to use DX12 and SM6 - even by using the simple Standard VR Template and switching to DX12 and SM6, will not work. “Mirage” effect even on simple geometry.

Thanks for any ideas, more infos, and recommendations when targeting the best visual VR PC solution.

Appreciate it!