This is the original source, linked on HN a couple months ago: https://christopherferan.com/2021/12/25/kenya-and-the-declin...

It seems like the collective washing and grading system was effective at producing high quality coffee (but not paying farmers a living wage) until the system got so extractive and climate change got so bad that farmers cut costs and started producing worse strains. In other markets buyers would go direct to the farmers for single-origin beans to encourage higher quality but in Kenya this was prohibited.