For the fan-forced mode on the label, the setting to be used is the one related to the forced air circulation function in accordance with the test procedures in the harmonized standard EN 60350-1:2016.
It could indeed be misleading that another mode than the one tested for the label is called “ECO”.
Disclaimer: Please note that the European Commission cannot provide a legally binding interpretation of the EU legislation, as this is the sole competence of the European Court of Justice. Any remarks from the European Commission services are without prejudice to the position the Commission might take should related cases arise in a procedure before the Court of Justice.