So there was a bug of random flashing of brightness in nighttime scenes in UE 5.51. This was fixed in UE 5.52. But now it’s back again in UE 5.53. This error was tested and we know it’s tied to Lumen. I don’t know why it’s back, But please fix it and then leave it alone. Also Hardware Raytracing still crashes on PC builds unless you add this:
[/Script/Engine.RendererSettings]
r.ShaderPipelineCache.Enabled=0
r.ShaderPipelineCache.StartupMode=0