I presume that estimation was accounting for that. The fact that signal power exponentially diminishes over distance is really challenging for us.

In the context of these distances Voyager has barely walked out the front door. It's just 0.002 Light Years away. At 100 Light Years away its signal would be 5 million times fainter than it is now, many order of magnitude below the detection threshold of any equipment that exists. No amount of listening with current technology would ever detect that energy level