What is this downtown side job during the Corpo prologue?

Solution 1:

This job is "Cyberpsycho Sighting: On Deaf Ears", which takes place in a mall parking garage. I could not identify it until reaching City Center. At the beginning of the game there's no way to reach that location, since the only way to leave the Arasaka office is with your boss's AV, which flies on a predetermined route.

My theory as to what causes the dot to appear so early is that it's part of the beginning tutorial on jobs. When you're in the office a popup appears explaining how the map works, and what key to press to switch between active jobs. They probably just show that extra job so players can try it out. Perhaps CDPR originally planned to have another side job within the office, but didn't have time to create that content so they just decided "unhide" a random nearby job to accomplish the same thing. Otherwise it would be a bug. Cyberpsycho sightings are among the first jobs to appear on the map after you start Act 1, but not until Regina contacts you about them.