Brown/Sepia frames when saving view to file due to unknown effect in unreal

I am trying to save a scene I am backplaying in unreal into PNG files.
The issue is that on certain frames the “skies turn brown”, something due to tone mapper makes brown/sepia flickers in the frames.
I have no way to disable it.
Also, I am curious why I cannot save into a Render target with RGB8 and only RGBA8, but RGBA8 gives me very dark result so I have to save into RGBA16f for some kind of a peculiar reason.
Is there a way in Unreal to save what I see in game to a file without frames flickering in brown?