We usually think of white holes as 'thermodynamically reversed black-holes', and this kind of membranes have not been observed in our universe. However, there is some other kind of 'topologically reversed black hole' which we know exists: our cosmological event horizon (CEH). It is reverse in the sense of the membrane direction where light cannot come out, the CEH allows outsiders to look in, but doesn't allow insiders to look out.
Question: How do GR describe in general reversed-orientation black holes like the example of our CEH? Please discuss the possibility that exact GR solutions where 'white holes' exist, we might be wrongly interpreting the solution, and what we rather should expect is a membrane-inverted black hole