Can anyone here confirm if this is in the game;

I was watching a certain streamer the other day and they were talking about how they came across a leftover area transition outline leading to the Upper City which they could click on, but didn't do anything because naturally there is no Upper City in the game... but apparently it's there and it wasn't removed properly, or something like that.

Is there really an area transition that was left in the game? I'm not in ACT 3 yet, so can't check myself.