Mostly, because this is 2020, and finding any indication of extraterrestrial life is out of the question in this burning trash-heap of a year :)
...But those results have since come under scrutiny, including from the original discovery team, which, citing a calibration error in one telescope it used, has downgraded the strength of its claim. Although the proponents remain confident of a phosphine detection, other astronomers have suggested that sulfur dioxide, which makes up most clouds on Venus, could have caused a similar absorption, among other critiques. ..."
"By late October 2020, the review of data processing of the data collected by both ALMA used in original publication of September 2020, and later JCMT data, has revealed background interpolation errors resulting in multiple spurious lines, including the spectral feature of phosphine. Re-analysis of data with a proper subtraction of background either does not result in the detection of the phosphine or detects it with concentration of 1ppb, 20 times below original estimate."
Haha! What's more likely, that a compound is produced in a way we dont understand or that some new life form exists in a way we don't understand?
If there were ever a time to apply occams razor that's it.