i assume you mean rapeseed oil??
i assume rapeseed oil has no markers against it Allergens or danger wise so probably because off a need to include some rapeseed oil rather than print new labels printed it on within the packing line capability would mean no extra cost or waste
"The government has agreed to suspend elements of labelling rules to allow retailers and suppliers to switch ingredients from sunflower oil to rapeseed oil without having to change labels"
It will be there as the date code printer can easily be changed on the packaging line whereas the rest of the film will be pre printed by the manufacturer and supplied to the company packing the product.