Wow I didn’t realize that Signal is run on Amazon’s servers and that they contract with the CIA. This article has some interesting points to mitigate the privacy concerns of this real popular service: https://simplifiedprivacy.com/signal-messenger-guide-to-avoid-privacy-mistakes/
That would be true if it was implemting forward secrecy.
The problem is that signal knows exactly who you know. I would use simplex chat or session