I currently use Telegram for my friends and family, but have reluctantly come to the conclusion that the UK Government is either reaching agreement for backdoors with messaging services, or is trying its hardest to.
I’m also on Element/Matrix. Before I try to get my contacts to join me on there, should I be aware of any privacy issues or is that a good place to head?
Telegram is probably the worst thing you could use, it doesn’t encrypt messages by default and they are stored on Telegram’s servers, so they can read them at any time.
Yes, Matrix leaks a bunch of metadata and doesn’t have post-quantum encryption.
The best option is to use Signal. It uses end-to-end encryption by default for everything: Normal chats, group chats, voice and video calls and even stories. Messages are only stored on their servers (in encrypted format, so they can’t access them) until you receive them, after which they are promptly deleted and only stored on your device. And Signal has much better metadata protection than Matrix. The UX is also much better and less confusing, making onboarding new users much easier.