Carbon dioxide was breathable fuel for cyanobacteria prokaryotes.
The oxygen was their waste product, and it poisoned them when the concentration grew too high.
They had to wait for natural weathering to take the oxygen out of the atmosphere before they had another cycle of flourishing.
"Cyanobacteria are a very large and diverse phylum of photoautotrophic prokaryotes... cyanobacteria are thought to have converted the early oxygen-poor, reducing atmosphere into an oxidizing one, causing the Great Oxidation Event and the "rusting of the Earth", which dramatically changed the composition of life forms on Earth."
The oxygen was their waste product, and it poisoned them when the concentration grew too high.
They had to wait for natural weathering to take the oxygen out of the atmosphere before they had another cycle of flourishing.
"Cyanobacteria are a very large and diverse phylum of photoautotrophic prokaryotes... cyanobacteria are thought to have converted the early oxygen-poor, reducing atmosphere into an oxidizing one, causing the Great Oxidation Event and the "rusting of the Earth", which dramatically changed the composition of life forms on Earth."
https://en.m.wikipedia.org/wiki/Cyanobacteria