Something that I muse about is that this bubble may indeed be a thin shell. My rationale is that already the bulk of our communications are confined to waveguides -- optical fibers. Our wireless comms continue to be engineered to produce less power and to be almost indistinguishable from noise. Much of our AC power travels along paired wires whose fields cancel one another at the equivalent of an inverse-fourth law or worse. Soon they may all be DC.

The civilizations who are "out there" may only have a narrow time window to pick up our signals. Like we've fashioned a poor man's Dyson sphere.

I think that an atmosphere with measurable oxygen gas is a far longer lasting, pervasive and interesting signal that by itself could prompt investigation.

The oxygen has been here for far longer than us, sometimes at much higher levels.

Nice article. I had to go down this rabbit-hole researching my first book. Actual likelihood of anyone actually being able to receive these past a few tens of LY is quite low without very sensitive receivers. Also as another commenter pointed out the window for receiving us is closing as more modern wide-band and spread-spectrum signals are more power efficient, directed, and look much closer to noise than data.