1. It's no secret that numbers tied to telegram accounts can be doxxed, and it costs very cheap. Moreover, since recently, Telegram specially prevents the use of fake numbers purchased on special services. Probably, this is done in order to sell anonymous numbers built into Telegram itself, which can be bought for the cryptocurrency TON, but the price is absurdly high - about 9 TON, or 19 dollars per number! Usually disposable numbers cost around 0,5$. The only left option is buying ready-made accounts, and mostly from services of Russian origin, which creates new security threats and is inconvenient.
2. The user agreement says that if you are accused of terrorism, Telegram can give the authorities the user's IP address and phone number. And while it says this has never happened before (which is probably not true), the mere fact that it's possible is enough.
3. But, while Telegram swears that it passed “exactly 0 bytes of information to the authorities,” Der Spiegel's report says otherwise: Telegram has repeatedly shared the personal information of its users/users with at least the German government.
4. Documents from developers of surveillance software for Russians, which turned up in the New York Times, reported that the FSB (russian FBI/CIA) can learn when and to whom users send data via Telegram and whether files are attached to messages.
5. End-to-end encryption is not available in chats, and is optional and inconvenient in private messages (it does not synchronize between devices).
6. Telegram client code is published in the public domain, but the server code is not. At the same time, the server part is the most important in terms of privacy.
7. Telegram is centralized. This means that, first, they can de-anonymize you, and second, they can censor you (which already has happened with *MANY*anarchist/opposition channels). Thirdly, even if they doesn't want to censor/spy on you, thanks to centralization, service still can be censored by a third party: eg. few months ago Telegram (as well as YouTube, Viber, WhatsApp, Vkontakte) started crashing a lot (the crash was explained by the inspection of special services and the adjustment of Roskomnadzor's gateways).
8. A small thing, but unpleasant: if you believe one (only) #truestory, Telegram support communicates with you without any respect
9. Telegram was created by a russian man (Durov) and that should not be forgotten. Once upon a time, the creator of Telegram, had a reputation for fighting russian censorship without fear or favor. Now, however, Durov's behavior raises huge suspicions. Back in 2020, Telegram was unblocked because Roskomnadzor “positively assesses the willingness expressed by the founder of Telegram to counter terrorism and extremism.” despite the fact that the original court requirements for Telegram, which led to its blocking, *were not met*. The unblocking of Telegram did happen just when Durov started having problems with his TON cryptocurrency and needed a large investment to keep Telegram functioning. As a result, we see the removal of the “Smart Voting” bot (biggest russian opposition bot) and the «fake» tag for the “Way Home” channel for wives of mobilized men. The aforementioned Telegram glitches have also already happened in 2024 on January 24: Andrey Suslov, Yakutia's Deputy Minister of Digital Development, attributed the malfunctions to preventive maintenance by Roskomnadzor.
11. Telegram's original promise to remain free and ad-free forever has been broken. Because telegram is not completely open source, it cannot be forced to keep that promise.
12. Recently, for the first time, telegram has begun to openly retreat from privacy in favor of commercialization, adding additional privacy features (such as the ability to comment anonymously (from the name of a closed channel), or see when other user(s)/s were online without revealing their data) only for those who have purchased a premium subscription.
13. There are absolutely idiotic vulnerabilities in Telegram: from the ability to calculate the IP-address (and using it — exact location and passport data through shady services) when making a call, to the accurate determination of the geoposition of a person who has enabled the “people nearby” function. (By the way, precise geo-positioning was once fixed, but has recently been made possible again.) If you do not set the settings correctly, it will not protect you even from threat model on the level of a schoolboy who knows programming — in other words, Telegram's settings are not set to privacy by default.
14. Recently, more and more opposition activists have reported that security services read their chats, and FSB officers quote their messages. Moreover, suspicious things have happened even in secret chats - for example, messages were marked as read, although it was known for sure that the interlocutor had not read them. Tho, this data is anecdotal
quotingWhy is Telegram horrible
note1gxe…glrx
--No MetaData Protection
(Who and When)
--Only Mobile is Encrypted
(Phones have insecure hardware) [1]
--Invented their own encryption algorithm
Unaudited with a history of security vulnerabilities [2]
--Most VoIP Numbers are Blocked
--Tor Often Blocked
--History of handing over to police [3]
--Centralized
--Forced Google/Apple Stores
(Telegram requires Google Push which is closed source,
So the binaries can't be compared to the code,
and therefore, Telegram's claim of "open source" is a lie)
Your friend will try to pressure you, claiming you're a fringe minority.
But if you repost this, we can be the majority.
(Sources linked in comments)