@Jopyth
thank you for the updated script!
the new script also shows me “Intruder detected” … i tried many variations of time and sensitivity adjustments…

I found another script on the internet:

from gpiozero import MotionSensor

pir = MotionSensor(4)
while True:
    if pir.motion_detected:
        print("Motion detected!")

This script shows me also the “Motion detected” all the time…
Maybe the PIR-Sensor itself is the problem… I will try with another Sensor next week :(