I think you're right. Just tried it with a TP Link Kasa smart plug with energy monitoring and it reads just about 20W lower all the time. Noticed the original power meter I used had a power factor readout that seems to be 1 all the time so it may not be that accurate. ThanksThat's strange, unless your meter is measuring the apparent power... at low load I've seen that the PSU has a slightly poor power factor; mine draws around 30-35W of real power (ie. the one that the power company bills the user for, at least for domestic usage here in Italy) at idle w/o anything connected.
I was expecting a lower consumption (the 25ish W written on the technical datasheet) but oh well.