In the official technical sheet it mentions that the temperature accuracy is +- 1 celsius not 0.1.
https://pim.beurer.com/images/attribut/DB_HM16_0414.pdf
Accuracy here means that the temperature shown on the display could be off from the real temperature by +/- 1 degree Celsius (or +/- 2 degree Celsius if the actual temperature is between 40 and 50 degrees Celsius). It has nothing to do with the fact that the display shows decimals.