IE like Crypto AG:
In 2020, it was revealed that the Swiss company, Crypto AG, which provided secure communications services to ~120 governments throughout the 20th century, was secretly ran by the CIA and West German Intelligence. The CIA and later NSA were able to read encrypted communications for many countries such as Saudi Arabia, Iran, Italy, Indonesia, Iraq, Libya, Jordan and South Korea.
Wait 'til you hear who invented it…
That said, considering how many illegal services continue to run on it, I don’t think it’s as porous as some make it out. Definitely has well-documented weaknesses but the project maintainers tend to address them fairly straightforward.
Of course, you’re also just as likely to be buying drugs off an Onion market that the FBI seized and kept running just to catch more bad guys, despite it also hosting illegal content itself.