The article wasn’t clear that doppler shift was accounted for, so a statement of fact that the signal was what it was can’t be made until doppler shift is accurately accounted for over time. Higher over time means it’s moving toward, lower over time means moving away.

After review: looks like it’s not been doppler adjusted... “And second, the signal “drifts,” meaning that it appears to be changing very slightly in frequency—an effect that could be due to the motion of our planet, or of a moving extraterrestrial source such as a transmitter on the surface of one of Proxima Centauri’s worlds. “