EFF has an incredibly thorough list of internet-accessible information that’s been curtailed as a result of anti-terrorism measures: information removed by governments, by ISPs, by website owners; you name it, this list has it. Not the information itself, but brief summaries of the type of information and links to articles discussing its removal.
Chilling effects of anti-terrorism
Posted by Ben on September 20, 2004
https://www.swordbilled.com/chilling-effects-of-anti-terrorism/