for example, they try to block telegram because they do not want to give them access keys to track users and their correspondence
That's factually wrong.
Telegram-the-messenger itself isn't blocked in any way, only the servers of Telegrem LLC company are.
That is due to the fact that the company ignored multiple legal requests from a criminal court considering a number of particular users been explicitly tied to 2017 Petersburg's underground terrorist bombing. The court requested access logs, account names per-phone-number and, I quote, "any additional info to assist the deciphering that particular chat logs". However, Telegram LLC (instead of any technical reply on the matter) just blatantly ignored court messages for about a year straight, then ignored another court rule that fined the company for that deliberate lack of response. As escaping fine charge is considered criminal activity for legal entities, Telegram LLC's further activity has been stated as illegal, thus its servers have been blocked.
Any problems with blocking "the messenger itself" is thanks to Telegram's architecture which supports only messaging via particular Telegram's servers without any possibility of direct c2c connections, even considering cryptographic keys generation between users (say hello to MitM design).
