Kind of ironic considering that with Matrix…

• Forward secrecy is kinda hosed
• they store metadata permanently on their servers by design
• A ton of stuff that would otherwise be invisible and signal is visible in your Matrix homeserver, including permanent history of all group membership
• Your data does not belong to you, and that’s how the server is built to treat it, e.g.
• GDPR deletion is nonexistent (it won’t delete your username or your messages, making it less effective than on Discord, let alone Signal)

… Etc.

Ironically, older federated messaging systems like XMPP might be better by coincidence. Message archiving was an optional addition and some servers, such as the popular Riseup one, do not implement it.