AVM thermostats are switched to heat at 0 am every day

Hi guys,

since the new heating period is around the corner I discovered that my AVM thermostats are turned on the the middle of the night for no reason:

I dont have any schedules on HA for that and only want to control them if needed. The schedule for the thermostats are on my fritz box at the moment:

In the log I saw the service “climate” turns all my thermostats at midnight to heat but I dont have any automations nor schedules to control them from HA. Is this a known bug?

Anybody got a clue?