Telegram has pushed out a new update for its Telegram Messenger Preview app for Windows Phone and Windows 10 Mobile. The app has been bumped to new version 1.29.28. The update has been pushed out and comes without any changelog. Currently there are no visible features or changes seen after the latest update to the application.
Hence we can presume that the update could be a bug fixing and performance improving update. The Telegram Preview App is currently not a UWP app but still a WP 8.1 app and the Telegram Team is working on making the Telegram Preview App a UWP app for both Windows 10 PC and Mobile.