As is tradition each year, Apple has announced the downtime window when the App Store review process will not be available.
Whoosh! Screen Cleaner
Giving developers almost a month warning, this year’s downtime window is the same at last year, December 23-27. Apple shared the following reminder on its developer website today:
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 submitted, approved, and scheduled in advance. Other App Store Connect and developer account features will remain available.