Was it this tire? https://www.bicyclerollingresistance.com/tour-reviews/panaracer-pasela-ptRear tire was different, as I have 559 (had Pasela 42 on it, runs quite fast, was inflated hard) and Snoek L is 700C (ran GP5000).
According to bicyclerollingresistance it has more than twice(!) the rolling resistance of a GP5000. That accounts for about 20W difference at the 55kph you were riding. So the major part of the difference in efficiency you measured between the two bikes would be explained by the different tires...