[BelleOfTheBall]

It is encrypted by default but end-to-end is only for calls and Secret Chats (one-on-one). You can delete any message at any time without a trace for both sides, which protesters often do, really don't think the government needs messages to pin a crime on them. Hell, they've pinned crimes on people for literally no reason before.

[vel0city]

So when you try and go tell the other person's device to delete your message, how does it go into their iCloud backups and delete that message, or some other backup?

Don't depend on asking someone else's device to delete the data as that data being gone.

[BelleOfTheBall]

Telegram doesn't store messages on the device, you don't need to "tell the other person's device" anything, it's deleted from the Telegram cloud.

[throwaway8941]

It is stored locally, although only temporarily. I rarely connect my phone to the internet and still can scroll through quite a bit of message history.