Real Madrid and other teams wear a pre-match top which is used just for warm up before the match. After warming up they will return to the locker room to put on the match kit.
Below is the kit used by Real Madrid for the season 2021/22 for pre-match appearance.
And the same kit from a different angle, perspective.
Finally is an image showing the top with the official name and number kit applied.
The printing is the official name and number kit 21/22 used with the away and the third kit. The players do not have the pre-match top customized thus you will not be able to spot this variation in the stadium. This is a service offered to the fan who likes the top but would like to add the printing as well.