I remember telling them years ago that the reliance on matrix was terrible. Are they still using it for the message passing though? They don’t mention what protocol replaced matrix, if any.
Discussion
It's in the blog post (no, it's no longer using Matrix): https://nunchuk.io/blog/group-wallet
All it says is that you replaced the keys. And the messages are handled with an “encrypted communication channel”. I assume that means that chats are hosted centrally on Nunchuk servers? There’s no mention of an alternative protocol for the message passing itself.