Gigaset motion's motion detection is based on infrared technology; therefore, false alarms are possible if there are major temperature fluctuations or reflections in the field of vision of your sensor. In some cases, this can result in you receiving notifications even if no one is moving around in your home.
For this reason you should ensure that there are neither intensive heat sources such as heaters or strong lights or large radiation-reflecting surfaces in the field of view of Gigaset motion.