In-Universe:
As the U.S.S. Defiant orbits Starbase 375 see the different ships as they overlap each other.
Production:
-- unknown --
The VFX team used the same shot of the Defiant and just placed different ships in the background. I overlapped them all to see so you could see how they used the same shot.
There is a VFX shot from 'Favor the Bold' with an almost identical shot as this but it was redone for some reason. I compared the angle of the starbase and they are different. Also the Defiant is orbiting at a different height. I wonder if they lost the original shot and just decided to redo it.