The team has DOD which says - The story is done when it is ok in pre-production enviroment and ready to release.
Our Review day is thursday and in company there is a common Deployment day which occurs on tuesday. It means, we complete our SPRINT on thursday and move our tasks to Done which is tested on pre-production which is not released yet.
On Friday we began new Sprint and take new stories from PB.
Deployment of previous sprint's stories takes time as well. The team must deploy its Done stories from previous Sprint on next tuesday.