The Ice Is a Byproduct of Microbial Life

The ice is unstable enough given the surrounding conditions, you wouldn't expect it to just be there from a previous freeze over it. And so back to venus, if phosphine gas were truly present at something 20 parts per billion, you would have to assume that something was continuously putting that phosphine there. It's possible the explanation was some geo chemical or photo chemical process that we don't understand yet. A very interesting candidate explanation was microbial life. The will of the wisp has so many strange and curious names a it has been given over the airs in different cultures.