Archived copy of the article

The key thing is that most of the offsets sold on these markets were fraudulent. This has been known for years, but the realization that a particular project didn't result in any CO2 removal was a big deal for the markets:

But a bombshell New Yorker article earlier this month asserted that millions of carbon offsets generated by Kariba, a giant project that earned nearly $100 million for purportedly preventing deforestation in Zimbabwe, didn’t actually prevent deforestation and preserve the carbon in the trees and soil.