Thermostat setting always dipping 0,1 degree.

[Menno]

First day I am cold, working from home, so I set the thermostat through Domoticz / Opentherm to 20 degrees.
And as always, if you take a look a bit later, Domoticz displays the setpoint as 19,9 degrees.
The actual physical thermostat (Remeha iSense) shows 20 degrees.
It is not the actual temperature in the room, that is (currently) 19,7 degrees.
Any ideas what causes this behaviour?