Earlier quoted context omitted.
People here will massively downvote your comment. The truth is that you are 100% correct in suspecting about that messenger. Since a long time that is known how Signal was initially sponsored by Radio Free Asia, which in turn is fueled by the CIA. For some reason western pages are disappearing on this topic, but after some search there are still some: https://greatgameindia.com/how-cia-created-signal-messenger-... Th…
Does the actual cryptography has anything suspicious-looking? I generally share your suspicion of the origins of Signal, but wouldn't the cryptography itself also look fairly odd if it were designed to be weak?
The problem with Signal (and anything like Signal) is not the server code, but the client code distributed through app stores. We have had email encryption for decades without ever having to trust any email servers.