If you dare to look into this topic, please also take a moment to look to another child protection non-profit[1] that (quite unusually) considers human and civil rights and sex positivity as one of its core values.
You might feel uneasy about "sex positivity" being associated with preventing child sexual abuse. They also have a lot of other messages that might initially repel you. But I also think that "when you associate shame and guilt with sex, you are facilitating sexual abuse"[2].
Here is a relevant Twitter thread about CSEM content filtering[3] and the secrecy around it. Secrecy that got them ejected out of a public National Center for Missing & Exploited Children meeting merely for tweeting about what was being said.
This Show HN open source project by Thorn seems to be an enormous improvement on that front. Would it be resistant to adversarial hashing (false positives)?
In my opinion, Thorn focuses way too much on technological solutions, and has an outright hollow message beyond that. Looking at 10+ of their website's pages, they don't dare to try to confront or explain the actual child sexual abuse itself, but only its most visible ill effects.
[1] https://prostasia.org/about/
[2] https://prostasia.org/blog/the-weapon-of-shame/
[3] https://twitter.com/ProstasiaInc/status/1178783074328424448