But they don’t have to know who the message comes from, hence why the sealed sender technique works.
Anyone who’s worked with centralized databases can tell you that even if they did add something like that, with message timestamps, it’d be trivial to find the real sender of a message. You have no proof that they even use that, because the server is centralized, and closed source. Again, if their response is “just trust us”, then its not secure.
The server is supposedly open source, but they did anger the open source community a few years back, by going a whole year without posting any code updates. Either way that’s not reliable, because signal isn’t self-hostable, so you have no idea what code the server is running. Never rely on someone saying “just trust us.”
They have to. They can’t route your messages otherwise.
I can’t speak about telegram, but signal is absolutely not secure to use. Its a US-based service (that must adhere to NSLs), and requires phone numbers (meaning your real identity in the US).
Matrix, XMPP, or SimpleX are all decentralized, and don’t require US hosting.
Post the video coward.