There are numerous factors that impact the room or current temperature measured by Mysa. Depending on the installation location, how the device is mounted, the type of wall material, and many other factors.
A 1-2 degree difference can also be explained by the fact that Mysa uses a smarter algorithm than a normal thermostat, which enables Mysa to find a more accurate room temperature. It factors in temperature, humidity, and how much current is running through Mysa.
When comparing Mysa with an external room sensor, do not put the external sensor on top of Mysa. The thermostat generates heat during operation which is vented out the top of the thermostat. This would significantly impact your readings. Below is an example of what not to do: