I agree that Telegram is an impressive piece of software, but it does not offer E2EE by default and the encryption model has been criticized in the past. Still, it is the best chat app in wide use anywhere in the world and this is a great achievement. Among other things, the client is open source and they don't ban unofficial clients, and they don't restrict you to a certain number of devices like some much worse apps. The channels is also a nice innovation, and Telegram has seemingly remained reasonably unwilling to comply on government encroachment (used by both sides in the Russo-Ukrainian war without too much suspicion). This is probably as well as a centralized chat app can ever do.