Your data looks as if some unit takes a break in the period before 4:00 AM. Then a regular cycle begins again.
My suspicion and that of some previous commenters is that it is a cycle consisting of heating, set temperature reached, heating off, temperature below the set value, heating on, set temperature reached, heating off, and so on. In the period before four o'clock there is a pause. This can be described as a setback. You can read that from the data, no matter what makes sense from your point of view and what doesn't.
And honestly, you are one of the most unlikeable questioners I have come across in the 3 years I have been reading here.