They lie about encryption. They call themselves an encrypted messenger when they're not, at least not in the way that people expect nowadays. I volunteered for their support team a few years ago but was rejected because the first test question was about their encryption and I refused to lie (I said regular chats are encrypted but only to the server, i.e. that Telegram can read your messages which was true then and is still true today, and that you need to use secret chats for encryption.)

I ended up adding a paragraph about it anyhow but that's why, when starting to write the post, I didn't add Telegram to the list. There is also rocket.chat further down that I didn't mention on top, fwiw.

it is?

I should maybe have put it in the list on top. I initially listed only the encrypted messengers, but later decided to add a paragraph about Telegram anyway.