To boot they produce o2 during the day so in a sealed room the o2 and co2 is quite high as they are independent... meaning just because one is high doesn't mean the other is low. But they hang onto much more carbon and plenty is converted to o2... so we don't need to supplement o2 but only co2.

The soil releases CO2 in two ways as well. The breathing of the microbes living in it and the plant is also driving down the pH of the soil by releasing CO2 into it to make carbonic acid. (The plant does this more when it needs phosphorus) The soil is also filled with microbes that consume nutrients 24/7 (CarbonNitrogenPhos and a bit of sulfur), take in oxygen and expel CO2. In a healthy soil you can produce a large amount of it. Much more than people would believe but I wont get into it other than saying its a lot.