When adding the UIRenderer to the Movie Render Queue, the rendering output is a difference in PIE and MRQ.

MovieRenderPipelineDataTypes.h

					float SourceAlpha = Src.A / 255.f;
					FColor Out;
#define BLEND_TEST 1
#if BLEND_TEST
					FLinearColor SrcL(Src);
					FLinearColor DstL(Dst);

					FLinearColor OutL;
					OutL.A = FMath::Clamp(SrcL.A + (DstL.A * (1.f - SourceAlpha)), 0.f, 1.f);
					OutL.R = FMath::Clamp(SrcL.R + (DstL.R * (1.f - SourceAlpha)), 0.f, 1.f);
					OutL.G = FMath::Clamp(SrcL.G + (DstL.G * (1.f - SourceAlpha)), 0.f, 1.f);
					OutL.B = FMath::Clamp(SrcL.B + (DstL.B * (1.f - SourceAlpha)), 0.f, 1.f);

					Out = OutL.ToFColor(true);
#else
					Out.A = FMath::Clamp(Src.A + FMath::RoundToInt(Dst.A * (1.f - SourceAlpha)), 0, 255);
					Out.R = FMath::Clamp(Src.R + FMath::RoundToInt(Dst.R * (1.f - SourceAlpha)), 0, 255);
					Out.G = FMath::Clamp(Src.G + FMath::RoundToInt(Dst.G * (1.f - SourceAlpha)), 0, 255);
					Out.B = FMath::Clamp(Src.B + FMath::RoundToInt(Dst.B * (1.f - SourceAlpha)), 0, 255);
#endif
					Dst = Out;