Step-by-step tutorial on desktop: The optimal dimension of the avatar on Telegram is 512px by 512px, and it’s recommended to use PNG format to deliver an unpixelated avatar. Public channels are public to the internet, regardless of whether or not they are subscribed. A public channel is displayed in search results and has a short address (link). But a Telegram statement also said: "Any requests related to political censorship or limiting human rights such as the rights to free speech or assembly are not and will not be considered."
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