I just read the piece at the link below entitled "Study: Life might survive, and thrive, in a hydrogen world."
I'd been thinking on similar lines recently, on different atmospheres with early life, but I was considering anoxogenic bacteria whose byproduct is sulfur instead of molecular oxygen. ¿Had life evolved on Venus could its sulfuric clouds be the signature byproduct of such life with no branches ever evolving to produce the equivalent of Earth's Great Oxidation Event and eventually creating a runaway greenhouse effect?
Study: Life might survive, and thrive, in a hydrogen world news.mit.edu/2020/study-life-hydrogen-world-0504
Anoxogenic photosynthesis https://en.wikipedia.org/wiki/Anoxygenic_photosynthesis
Clouds on Venus https://www.universetoday.com/36871/clouds-on-venus/