Weird: Homeatic IP Thermostat is running wild

Dear all
I have one thermostat where I really do not understand why it turns suddenly from “auto” to “manual” mode…

No physical interaction is involved. The homeatic ip App has also heating plan but that should not be the cause.

I see in HA the following

entity_id=climate.schlafzimmer&start_date=2022-01-30T23:00:00.000Z#) changed to Heat by service climate.set_hvac_mode

I do not have any automation or so which are using the service…
Mysterious!

Any recommendations whre I can investigate further to see what triggers that change to “manual” by the service?

Best regards

Ralph