Apple has recently announced its holiday schedule for December 2019.
The following message was announced in the Apple Developer site on November 29, 2019:
|The busiest season on the App Store is almost here. Make sure your apps are up to date and ready for the holidays. New apps and app updates will not be accepted December 23 to 27 (Pacific Time), so any releases should be scheduled, submitted, and approved in advance. Other App Store Connect and developer account features will remain available.|