It doesn't mean the Great Filter is ahead of us, it means it applies to Mars.
Mars lacks the proper magnetic field to retain an atmosphere. The Earth does not. Mars experiences substantially less solar radiation, which means less opportunities for photosynthesis, but due to a lack of Van Allen belts substantially more ionizing radiation, which means more opportunities for sterilization.
There's an "and then a miracle occurs" segment in all discussions of the Fermi Paradox: it is presumed that intelligent life manages to get around the limitations of Newtonian mechanics, and that whoever might be out there is obviously a Kardashev 2 or better civilization. Also, very little attention is paid to the fact that the majority of our SETI attempts are focused on our communications strategy from 1921 (first shortwave broadcast) to 1948 (first cable TV system). The overwhelming majority of our communications these days are over fiber optic cable, which isn't even discernible from other cables in the jacket. Most of the communications we're leaking out into space at this point are directed energy broadcasts at our own probes, and even those are minuscule from an interstellar standpoint.