A crazy thought appeared. If you need the NPC to survive a fall and be able to continue searching for the player using navigation, you can calculate the nearest landing point on NavMesh at the moment of the jump. Thus, the trajectory of the NPC’s fall will be set along a parabola towards the desired point. If the point is found, the character will survive; if not, it is easier to kill or prohibit the jump.
If an NPC falls into an area where there is basically no navigation, is there any point in finding out whether there is one or not?)))