I don’t currently use Unreal Engine 5. The benefits were mostly aimed at open world stuff, and did not yet outweigh the cost of fixing all the issues that came up while porting my 4.27 VR project.
What I can tell is that the cvar (CVarDrawToVRRenderTarget) was checked in FSlateRHIRenderer::DrawWindow_RenderThread
The comment for the cvar had the text “for better or worse” in it, so it’d make most sense if they just removed the weird behavior of drawing to the HMD, removing the need for the cvar, but given that you’re posting here, I guess they didn’t? You could check the source code for 5.5 to see what changed to slate rendering, and where they’re drawing to the HMD render target, and how to disable it.
Otherwise the work-arounds I started the thread with might still work.