Atomic clocks are subject to vastly different conditions in space, vice on the earth. Different gravity, different radiation, etc.
The answer is that the accuracy of the measuring device is infinitesimally different in space, not that “time slowed down”.
Unreal how deeply sci fi has penetrated the modern brain.
Einstein was not sci fi. Sci fi stretches a lot of truths but relativity, both special and general is real and can be measured. Again you are speaking from your butt. Go back to school and take some physics.