The scariest part of this recent news is that TM Signal seem(ed) to be interoperable. People using TM Signal could interact with actual Signal users. How are you to know whether or not your groups have people using bastardized versions of Signal? Are things like Session interoperable with Signal?
I mean… you do know someone can just take a screenshot, right?
And even if you use the Android thing that blocks screenshots, they can still take a photo with another phone.
You need to trust the other person for there to be any “privacy”.