I don’t know beans about this stuff, although I find it fascinating. One question that comes to my mind is we evidently only see one side, what’s happening on the other side?
Being a bridge to another co-extent Universe is just one theory. Not being able to observe the other Universe is kind of a big barrier to confirmation.
My theory is that black holes aren’t permanent. Merging and/or colliding black hole masses could very well rip each other apart to a point where they no longer hit that Schwarzschild density.
Logically, Hawking radiation and Unruh are tied to the same space/time frame phenomena... This alone provides a more than adequate mechanism to “drain” energy out of a black hole and plays havoc with the “big bang/big crunch” mathematics...
Supposedly we are seeing light from 13 billion years ago. As far as we know that object is now gone. Have to wait a coupla’ years before it’s light goes out.