Recent chats are displayed in the iOS Share Sheet when you share content from an external app. E.g.: When you share a photo from the iOS Photos app.
This feature won't work if:
• You disabled all categories in Settings > Data and Storage > Share Sheet
• You set an in-app passcode in Settings > Privacy and Security > Passcode & Face ID
• You have iOS 13.1.3 or older (this feature requires iOS 13.2+)
Note: You can choose which chats are displayed in the Share Sheet by going to Telegram Settings > Data and Storage > Share Sheet (under Other).