The SceneTexture:WorldNormal is not taking in direction for color when used on deferred decals. As a result, the decals using this node always show up as grey.
Tested in 4.21.2 (CL - 4753647), 4.22.1 (CL - 6063286), 4.23 (CL - 6682473)
Expected: the Colors for the decal would be red, green, and blue based on the direction
Result: All of the colors are gray
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-75451 in the post.