I've never experienced anything like that on 2 rear hub drive and 2 mid drive bikes. The geared hub motors have a very small drag you can't even detect when riding. You can only notice it when spinning the wheel on a stand and it runs down slightly quicker. The mid drives have no difference at all due to having a freewheel type ratchet in the bottom bracket/motor area.
What you do notice especially on the Bosch motor eMTB is the contrast between assist on and off due to the weight of the bike, i.e it's really hard work to go above the assist speed unless downhill.
What you do notice especially on the Bosch motor eMTB is the contrast between assist on and off due to the weight of the bike, i.e it's really hard work to go above the assist speed unless downhill.