Why does the fan of my dehumidifier purchased after 01/01/2020 not stop in automatic mode or restart from time to time?

The regulation of dehumidifiers has changed on 01/01/2020. Your dehumidifier now works with R290 gas, as required by the European Union from 2021, for all devices containing a refrigerant gas. Depending on the quantity of gas contained in the device, the fan must either remain on when the compressor turns off, or restart from time to time (duration varies depending on the manufacturer) to re-measure the humidity level. This is completely normal and complies with a European safety standard (EN 60335-2-40 concerning "Household and similar electrical appliances - Safety - Part 2-40: Particular requirements for electric heat pumps, air conditioners and dehumidifiers").