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?
Moxie has resigned a few years ago. The article you linked to is 9 years old, Signal leadership has changed a bunch of times since. Signal can’t detect that you’re running an alternative client, because that check would require them to include some new code in the official client. Even if they did this, they couldn’t just ban anyone who’s client doesn’t pass the check, since it could just be an older version of the official client. They could force everyone to use the official app, but they really have no reason to invest time and effort into enforcing this. Molly is only available for Android, and it isn’t even on the Play Store or the official F-Droid repo, so the user base naturally won’t be as big.