The original contractors in the TENET universe must have felt odd, installing shattered glass into a new frame and being unable to spackle-out bullet holes in the walls they were building...

nor able to sweep up brick dust on the floor for decades because it is "destined" to be reverse-bullet damage that is fixed in the future.

(In the movie, you see them walk into a pre-damaged room that is later 'repaired' by the inverted gunfire that caused it)