Yeah, this one's common. Your door/window SmartSensor is either falsely triggering or the 'Pause when Open' feature is misconfigured.
First, check which sensors are participating. On the thermostat or app, go to your eco+ settings and find 'Pause when Open'. See the list of enrolled sensors. You can disable specific ones there. If you turn them all off, the feature turns off completely.
If that didn't work, the sensor itself might be faulty or its magnet contact is weak. Check the physical sensor on the door/window. Ensure it's mounted correctly and the contact is secure. The feature triggers after an opening is detected for more than 5 minutes.
Heads up: This feature requires a SmartSecurity subscription and a door/window SmartSensor. It also needs your thermostat to be connected to the internet to initiate the pause. If the internet drops after a pause starts, the system will still resume when the sensor is closed.