Not a fan of Telegram, but as far I understand this only let's you scrape messages from public channels. People shouldn't really expect anything else when you write a message on a group with 100s of other people
Exactly, and this tool even joins the channel. I mean what else do you expect, it's not a surprise that anyone who joins a channel can read the messages.
Not untrue. And its one ngnix ec2 instance away from silently changing it from anyone who joins a channel to read the message to the world indexing all those messages.