The story of those co2 bags is that mushroom mycelium produce CO2 as a by product. The bags full of substrate and inoculum were widely sold at the time for a variety of mushrooms and amateurs to grow mushrooms from.
Now one day a certain grower on a certain site put 1 and 1 together to come up with 3 and pondered that he could use that small amount of co2 from his mushroom bags to increase his cannabis crop.
All this checks out as plants in increased co2 can biologically exceed normal maximum growth with CO2 being the limiting factor.
But disaster struck, the bags produced such small amounts and almost all was swiftly sucked from the tent by the extraction.
Although this didn't stop some seeing some dollar signs and bro science from evolving this mushroom growing bag into a repackaged cannabis product.
And here we are today with them still being widely sold...