A child porn instance would have cops breaking down the server room door
Burggit.moe does synthetic child porn, stuff like loli/shota material. That's First Amendment-protected in the US (and is apparently legal in the Netherlands, where the server says that it lives), but is illegal in a number of countries in the EU.
piracy-friendly instances
lemmy.dbzer0.com was created specifically to do piracy stuff, and is one of the major Threadiverse instances. And db0 himself has contributed a fair bit of software to improving Threadiverse infrastructure: