“Signal is being blocked in Venezuela and Russia. The app is a popular choice for encrypted messaging and people trying to avoid government censorship, and the blocks appear to be part of a crackdown on internal dissent in both countries…”
Couldn’t they block them too? Monitor the domains people connect to, check if it’s a Matrix server and block it if it is.
The overwhelming majority of users are on the main servers. It also impacts self hosted Matrix servers that use the matrox.org identity server.