Danfoss / POPP thermostat: turning on by itself

Including with VeraEdge went fine, although I don’t understand the settings, see my other topic.
But I experience very weird behavior:

With Vera (or on the unit) I set it to 24, I hear it opening and radiator is getting warm, then
I set it to 5 !!! degrees. And I hear the motor running and closing the valve. So far so good.

I left it like this and checked every half hour. And guess what, after around 4 hours the radiator is warm.
Why o why is the POPP turning ON? With 5 degrees it should NEVER turn itself on, never! Of course temp in the room is far above 5.

Does someone recognize this? With the Danfoss or better the POPP thermostat, as this is the “improved” LC13.

i read somewhere, there is a “auto-on/off” function, whereby if the thermostat detects a strong change of temperature (ie cold draught from a door or window open) it changes state to compensate. (Cant remember if it was turn off to save energy or whack-it-up to restore heat)
dont know if this is auto or selectable.

Similarly, and in know its not the answer, i understand the device does a full open and close on a regular interval (Weekly) to ensure it doesnt seize up.