As always, none of the numbers are official, so take all of them with a huge grain of salt. The article also doesn't link to a single source, not even an unofficial one.
> Assuming an even split of sales between Gen 1, Gen 2, and AirPods Pro, Airpods revenue was $12 billion in 2019
This itself is a terrible assumption. AirPods Pro launched in November 2019, so had just 2 months of sales. Even otherwise, there is never an even split between the lower and higher priced versions of any product, especially when the higher one costs nearly double.
> Assuming an even split of sales between Gen 1, Gen 2, and AirPods Pro, Airpods revenue was $12 billion in 2019
This itself is a terrible assumption. AirPods Pro launched in November 2019, so had just 2 months of sales. Even otherwise, there is never an even split between the lower and higher priced versions of any product, especially when the higher one costs nearly double.
Another source (https://hypebeast.com/2019/12/apple-airpods-stats-third-larg...) estimates the sales at $6 billion, half of what the parent article says.