Thermostat off despite target temp not reached

[av13ebuy]

Hello

I am a newbie and I am a bit lost.
I have installed this thermostat, however I do not understand how it works.

I have a temperature of the room in the picture at 19.4C.
I have requested 19.9C but my thermostat does not make it on to reach the target temperature.
Can someone explain me the "reason"?

thank you for your help :)

[jmcollin78]

Hello, please read this: https://github.com/jmcollin78/versatile_thermostat/blob/main/README.md#algorithm