Any centralized chat protocol is prone to centralized control. This is why Signal Messenger is also affected.
Opting-out of this threat is only possible by using a decentralized protocoll that can also be easily setup by individuals.
Matrix is practically centralized as the majority of its users is on one server, probably due to the setup being not so easy.
There are decentralized protocols that are also practically decentralized. First coming to my mind: XMPP. Many servers offer sign-up for free. If someone wants to setup their own server instead, it takes an hour with Prosody including all configuration. They made it particularly easy as decentralization is their selling point.