They have APS
Just wanted to add on something of note to this old thread.
If you pay attention to the spacing of the Gepards guns and Pantsir S-1s, they are very spaced apart, so depending on the flight path of the drone it will miss most of the time, especically since both don’t use programmable ammunition. Compared to vehicles that have their weapons center mounted.
The Gepard has gained it’s reputation hitting mostly larger targets and not off of hitting much smaller handheld drones.