While enabling Ray Tracing from the start of the project, when user sets GlobalPostProcess Translucency to Ray Tracing, the back-face of the plane is not culled. However, when the translucency is set to Raster, the actor is culled as expected.
This was tested and reported in 4.26 Preview 3 (CL-14488950). This was reproduced in 4.25.3 (CL-13942748) and 4.24.3 (CL-11590370)
Outcome: the plane is only culled when translucency is set to Raster, when it should be culled with Ray Tracing enabled as well. When Ray Trancing is enabled, the back-face of the actor is not culled.
Expected Outcome: The plane or actor should be culled after selecting ray tracing in translucency
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-101791 in the post.