Filtered how? By some keywords I don't want to know? What about encrypted zips of CSAM? There's no way to filter that in reality.
If you want to learn more about why and you can either speak German or can handle youtubes auto translate i recommend this documentation on the matter[0]. The Pedo Criminals are using scene methods to share their illegal content.
I guess you could filter all torrents that include just zips/rars/7zips. That would exclude a lot of harmless content. Probably too much harmless content to make it a default, but if you only care about hollywood releases it would be a useful filter
If there was a public list of hashes of (8/18KiB blocks of) CSAM content that would be useful for a filter, but I don't think such a thing exists