Just... Why would they bother to hide a bunker a Washington DC? They'd just say they built a bunker in Washington DC. I don't think anyone would be particularly shocked that they built a bunker for Congress in the general capitol region.
Just like no one was shocked that they evacuated Congress through the capitol buildings egress tunnels on January six.
I think the more surprising thing would be if they put a bunker under a prominent statue that would be a target in its own right.
Not that they don't have secret bunkers, I just don't think they would put it under a target directly adjacent to where everyone would expect a bunker to be.