Federation makes it much harder to keep metadata private, though you could technically achieve the level of privacy found in Signal, it’s not easy.
In practice, Signal is a lot better at protecting your metadata than Matrix and XMPP.
Now that matrix has a lot of different clients and implementation, of would be super hard for them to implement something like Sealed Sender, which Signal was able to deploy very easily. I find it very unlikely that matrix will end up fixing its privacy issues. While Signal will be able to evolve and fix them. They are currently working on usernames for example.
Federation makes it much harder to keep metadata private, though you could technically achieve the level of privacy found in Signal, it’s not easy.
In practice, Signal is a lot better at protecting your metadata than Matrix and XMPP.
Now that matrix has a lot of different clients and implementation, of would be super hard for them to implement something like Sealed Sender, which Signal was able to deploy very easily. I find it very unlikely that matrix will end up fixing its privacy issues. While Signal will be able to evolve and fix them. They are currently working on usernames for example.