https://www.scientificamerican.com/article/lifes-small-molecule-problem/

The recent claim for a detection of the molecule phosphine in the Venusian midlatitude cloud layers has brought the idea of chemical biosignatures back to the forefront of attention in our efforts to find signs of life elsewhere in the universe. Phosphine, the argument goes, is not generally expected to be produced, or to survive for very long, in the abiotic (nonliving) chemistry anticipated for this part of Venus’s environment. But on Earth phosphine is associated with organic matter (think swamp gas or sewage) and could be argued to be a biomarker or biosignature molecule of certain extreme organisms that might have cousins or convergently evolved equivalents lurking in the sulfuric acid clouds on Venus.

Not surprisingly there are a lot of caveats. A lot of caveats.