I am trying to move my Discord community to other platform, due to privacy issue, any recommendation?

Matrix? That's the open source and federated equivalent to discord. And it's end-to-end encrypted.

Matrix is very good and flexible. If you need something that is interface-compatible with Discord, there is: https://revolt.chat/

Matrix is the usual suggestion. I've never used voice chat on it or the clients for it like Element though so I can't speak to how well it works if you need that function in Discord.

You answer is Matrix, it has a learning curve but is robust.

ig Federated platforms are not as secure as decentralized platforms.

Revolt is an open source client with a similar feel, but streaming doesn’t seem to work yet.