Now it is really weird. The parasitic drain depends on the ambient brightness.
The current of 1.88 mA drops to 40 µA after some seconds, but only in a dark environment . The light did not do this current change during my first measurement (duration 2 min). I have no idea what triggered the change in the driver’s behavior.
Anyway, if the light is stored in a brighter environment (1000 lx) the drain goes up to 0.33 mA, and in sunlight (over 100000 lx) it sometimes jumps over 1 mA. This is caused by the IR sensors. They induce a current which is generated by the ambient light.