This article needs more details. My understanding is that 4chan delegated much of this responsibility to CloudFlare for illicit image detection. I have no idea how comprehensive and reliable their service is and would be curious if anyone else here has used it or is using a self hosted detection model that downloads some type of heuristic database. My reasons are entirely selfish as I still use the old school model of being alerted on POST's and manually review on my tiny sites.
The problem is that if the media admits that sites such as 4chan make a good-faith effort to combat illicit images (as in seriously illicit, not whatever vague, low bar the UK sets for when something is "harmful"), that makes it harder to slander these sites as CSAM distributors.