What is the hypothesis of oxygen revolution?

Oxygen revolution:

1. At the start of the formation of the earth's atmosphere, oxygen was barely present in the elemental form.
2. The earth's atmosphere was composed of carbon dioxide, methane, hydrogen, sulfur dioxide, and other reducing gases.
3. Thus, the persisting atmosphere was reducing in nature without any trace of elemental oxygen.
4. As the vegetation began to take over the planet, plants performed photosynthesis.
5. This liberated oxygen into the atmosphere.
6. The initiation of the oxygen revolution started with cyanobacteria producing oxygen through photosynthesis.
7. The occurrence of primitive autotrophs from heterotrophs on earth, when oxygen was limited should be stated.
8. Water bodies formed due to the moisture liberated from trees and aquatic plants flourished.
9. With human civilisation and animals coming into existence, respiration, burning of fossil fuels, and other activities began.
10. An overall rapid oxygenation event occurred.
11. Thus, the reducing atmosphere transformed into an oxidizing atmosphere.
12. This conversion of the reducing atmosphere into an oxidizing one that occurred over 2,400 million years ago is referred to as the hypothesis of oxygen revolution.