I do not recommend using Telegram.
There are no encryption keys here, and there is no complete privacy for the user. This is a common social network.
The first thing you should pay attention to is that registration is possible only via phone, although other messengers can register via e-mail. Knowing your phone number, the government will know all the information about you, including your passport, date of birth and other sensitive data.
Second, If you are subscribed to some channel(s), then another user can find out by clicking on the profile icon if he is in the same group with you.
Apart from this, there is no evidence that messages are transmitted through encrypted keys. If this were actually the case, then you would see these keys, since there would be no point in hiding them, since they are individual for each user. Beyond that, the messages would be encrypted if you didn't have the necessary decryption key.
If you are in any group, then the official Telegram bot, Spam Bot, can ban you for nothing.
I have had several such cases. In the first case, this bot banned me for nothing, when I was just in the group, and the second time, when I sent a harmless photo to the conversation, this bot blocked me again, for 1 month. And during this month, I did not have the opportunity to write to new users, as well as enter new groups and channels.