The manual unread mark of a chat was changed
updateDialogUnreadMark#e16459c3 flags:# unread:flags.0?true peer:DialogPeer = Update;| Name | Type | Description | 
|---|---|---|
| flags | # | Flags, see TL conditional fields | 
| unread | flags.0?true | Was the chat marked or unmarked as read | 
| peer | DialogPeer | The dialog | 
| saved_peer_id | flags.1?Peer | If set, the mark is related to the specified monoforum topic ID ยป. | 
Telegram supports direct messages to channels, which can also be used to suggest (even paid) channel posts.