Just saw your post.
It works as expected. I didn’t see any artefacts.
You can follow instructions here to enable oculus branch + enable tonemapping.
And this is how I called the fade in C++:
CameraManager = UGameplayStatics::GetPlayerCameraManager(GetWorld(), 0);
CameraManager->SetManualCameraFade(MyFadeValue,MyFadeColor, false);
MobileHDR is disabled in my build. Using UE5.1