That’s because the AI are quite effectively using cameras to get at you before you even see them.

The skill gives you a yellow damage indicator and highlights the hacker in yellow outline.

The camera one is easy to fix and I found it to be a fair mechanic. However the bug here is even all camera is disabled (either via a daemon, turning them off individually, or shooting them down, or even in area with no cameras, e.g. Nash part in Ghost Town quest) they can Overheat you from behind a solid wall or even in a different room.

My guess is this is similar to enemy sniper sometimes can see you through walls. If they're close enough to a wall, then their line of sight is calculated as if they were in front of a wall.