It seems, that the AI of Arma3 determines any UAV regardless of its size at the same distances and does not take into account the specific of the UAV unit. For example, such a small UAV as AR2 Darter and its analogs can be easily detected by AI infantry at great distances. If I use such an enemy drone in my missions, then the AI in my squad will report: "Contact - UAV 500 m - West" or "Contact - UAV 600 m - East" or "Contact UAV 700 m - Noth-West" etc.
The 500-600-700 m - visual distance for the detection for such a small drone looks absurd, since such a small object can not be seen visually at such a distances. BIS please reduse visual detection range for detection small UAVs by infantry. The purpose of this tweak -To make a small drone a more realistic and more dangerous device for observing. Because of its small size, this should be less visible to the opponent's eye