Information comes out of black holes. That’s the whole point of the Hawking radiation thing. And information enters, obviously. Also those few basic measurements are information. Black holes are falsifiable and detectable.
Causality inside black holes is not like causality out here, but it does exist. Once you enter, there’s only one direction you can go, no matter what you do. The outcome of everything was decided the moment you touched the event horizon. That outcome is that you will eventually evaporate as hawking radiation.
I’m not glossing over the point. I’ve already addressed the crux of it. An environment in which systems can be totally isolated cannot function in any conceivable way as a universe. Everything inside would not be able to interact at all. It would be more like a substrate on which universes exist, if an environment can be isolated that does not allow for anything inside it to be 100% isolated.