>Through what right or means can Apple demand this, though? I imagine that it's through the terms of the contract signed by Telegram to be allowed into the App

>Through what right or means can Apple demand this, though? I imagine that it's through the terms of the contract signed by Telegram to be allowed into the App Store. That Apple is flexing its market share (and walled garden) to enforce those terms on Telegram isn't even unusual. But that doesn't make it ethical or right.