“Telegram clearly fails to meet this stronger definition for a simple reason: it does not end-to-end encrypt conversations by default.”
Telegram’s Secret Chats take four clicks through hidden menus, work only if the other person is online, and never cover group chats. The user-facing design is almost unchanged since 2016 while the user base grew 7-9x. Durov still markets it as a secure messenger. A messenger that encrypts nothing by default is a cloud database with a privacy brand.