Clarification regarding ephemeral messages in channels and groups.
There are two types of messages: Unanchored and Anchored.

× Unanchored (shown in the first screenshot) creates a separate ephemeral message in the channel. It can be deleted manually or will disappear after some time.

× Anchored (shown in the second screenshot) replaces the original message with an ephemeral one. By pressing and holding the message and tapping «Revert», you can restore the original message.

Telegram Beta for iOS v12.9.3 (34570)
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Welcome Ephemeral Messages can also be configured in channels.

After joining a channel, the user will be shown an ephemeral welcome message. The video only demonstrates an example of how this may look.

Telegram Beta for Android v12.10.0 (7000)
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