I want to believe.
Do we have an actual way to proof this? In SimpleX we do know exactly how it works. So if in doubt I'dcalways vouch for SimpleX.
Signal/Molly is what I use as a backup network.
Discussion
Signal Messenger is Open Source as SimpleX, more over, both have upgraded their encryption to level of quantum resistant...
This matters, most believe that if you are using a service that is e2ee you are good, but you are not.
Why?
Cyber Criminals and I will assume most three letter agencies are collecting all raw data they can from centralized services/servers and storing them for future decryption, clearly, if your cloud service is not upgraded or your messenger service is not resistant, all the data will be open for cyber criminals and agencies to look at...
I keep advising family, friends and clients, stay away from centralized services if possible and if not, verify they are upgraded if they use encryption
Problem with decentralized messengers is that now that data lives on MULTIPLE sources. And openly accessible ones.
So E2EE messages in 1 location are still more secure than in multiple locations, if both have the same encryption level.
The most safe is messages stored on zero servers: P2P.
P2P should be every messengers aspiration.