I find it highly amusing that people on here actually think secure messaging platforms are "locally backdoored".
Despite what the article says, Telegram is not even a nominally end-to-end encrypted platform. You need to jump through hoops to get end-to-end encryption on the platform.
On Telegram, even private messages are not end-to-end encrypted by default. The so-called secret chats are end-to-end encrypted but are a major pain to use.