https://arstechnica.com/science/2024/08/was-the-wow-signal-actually-a-space-maser/
Magnetars could zap clouds of atomic hydrogen, producing focused microwave beams.
TL;DR: Interstellar hydrogen clouds could act like a naturally occurring galactic maser (a mechanism to amplify microwaves like a laser amplifies light), emitting a beam of intense microwave radiation when zapped by a flare from a passing magnetar (a neutron star with a very strong magnetic field).
Wasn't this already the leading hypothesis behind the WOW signal? I remember reading about this many years ago.
Whether it was or not, the article is talking about two scientists who see emissions similar to the WOW signal all the time just with far less intensity than the signal. They made the connection and extrapolated how it might be possible to see something like the signal.
Apparently there was an idea about two comets interacting with the hydrogen cloud proposed in 2017, maybe that's what you're thinking of? https://web.archive.org/web/20220509154206/http://planetary-science.org/research/the-wow-signal/
Swamp gas from a weather balloon was trapped in a thermal pocket and refracted the light from Venus!