On sites that serve user-generated content, how would one technically detect if one's ads are being served alongside CSAM? Wouldn't the ad source need to be abl

On sites that serve user-generated content, how would one technically detect if one's ads are being served alongside CSAM? Wouldn't the ad source need to be able to fully read the contents of the page itself? Are there good technical solutions to that problem? And whose responsibility is it to solve - the ad source, or the platform through which CSAM is being served? Definitely something that needs solving, but sounds really hard to solve - unless you just don't serve ads on that site at all.