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Turn on r.Shaders.Optimize=0 cause Z-Fighting problem using forward shading

The problem disappears when I reset rotaion to (0,0,0) or turn off Use HDRI, I’m using UE4.23. Anyone can help, thanks.
https://github.com/comfanter/ZTestFail

What happens if you check the “Use Camera Projection”.

Edit: Oh, nevermind I thought you are using the hdri backdrop actor.