A temperature fluctuation of +4°C/-3°C is normal, since the temperature is controlled by switching the heating on and off.
This results in a temperature curve. It is possible that the temperature will initially exceed the target temperature, by up to 5°C, especially when heating the vaporizer from the cold state.
If you believe that your device needs to be serviced, please register it in your customer account. Based on the malfunction and its warranty status, either an RMA can be initiated or a repair can be purchased.