Apparently this is really a bug. Like I said, I just migrated the scene into the engine and didn’t change anything in it. The main parameters are identical, and they should not have changed. Yes, there is a post process in the scene. The only thing that is different is that in 5.3 I have DLSS installed and activated, but can this really affect the world? I mean, everything looks like this even in the viewport, if nothing is rendered, and there was no 5.4 DLSS either, but there the scene looks exactly like in 5.3.