Microsoft has been somewhat inconsistent with sharing release notes for new versions of Skype in the Insider program, but today, the company posted the changelog for version 188.8.131.52, which is now available for Insiders. The update doesn't revert the transition from the previous Microsoft Store app to the classic desktop version, but it does include some improvements.
While the list includes a few changes, it's worth noting that some of these features may have already been available. For example, today's changelog mentions that it's now possible to share files directly from the File Explorer to Skype, but this feature was also mentioned in the official changelog for Skype version 8.58.
There are a couple more improvements, though, such as new call controls in the Recent Chats list, which now show the call duration and an option to end the call directly from there. Following up on the newly-added ability to delete contacts directly from the contacts list, Microsoft has now added the option to delete multiple contacts at once by holding down Shift or Ctrl while selecting the contacts to delete. Finally, users on iOS can now search for any available Skype subscriptions.
Microsoft says these features are rolling out gradually, so you may not see them right away.