Telegram isn't end-to-end encrypted unless you're in a "secret chat", and that chat exists only between two different devices and can't be used by multiple devi

Telegram isn't end-to-end encrypted unless you're in a "secret chat", and that chat exists only between two different devices and can't be used by multiple devices on one account. It's a "feature" of the normal chats/channels/groups/supergroups of Telegram that you are able to download them to other devices, or to restore them on a freshly wiped device, because (and I'm over-simplifying here, but the end result is the same) they are encrypted with a key known to the server, and which other devices signed into your account can then be authorized to use.