I wrote this sentence. “closed proprietary” here means that it’s not an open standard, and it’s not an open network you can connect your own clients to, and so

I wrote this sentence. “closed proprietary” here means that it’s not an open standard, and it’s not an open network you can connect your own clients to, and so it’s vendor-locked, and in the case of Signal there are gaps of years when they don’t release opensource code on the server.