Is this a problem with my Haibike or is it me?

Result.
It was the third derailleur adjustment that solved the problem.
The high and low stops were good but the chain tensioner was way loose.
As I moved into the higher gears (smaller cogs) the derailleur flattened and did not maintain good tension.
Getting that adjustment took just 2 rides to work out.
I had the tuner replace the chain and it appears they did not reset the tensioner back to spec.
Live'nLearn
 
Kind of an E-bike newbie here myself too...but I noticed the same thing on multiple bikes that I tried. I did end up buying one and was feeling it too, but I think I've wrapped my head around it.

The motor is either cadence-sensing or torque-sensing (or both). If you stop, even for a second, there is neither cadence or torque to sense so the motor cuts off. When it stops, it feels almost like it 'jerks' or 'pulls' (when I first felt it, I thought the brake was being mildly applied). But all that's happening is that the motor stops and suddenly without the assistance, the heaviness of the bike with no motor (especially if you are going uphill) suddenly feels like it's pulling BACK.

I think that's what is going on when I felt it...so try to determine if that may be what is happening with you too. Pay VERY CLOSE attention to when it happens. Did you "just" stop pedaling that moment?
I am new to ebiking too and I think you hit it on the head. I have to go up a 250 foot hill to my house from the main street. I am already shifted down and in Turbo....I must be going so slow that the system cuts off....and it is pretty scary to feel the full weight and instantly need insane force to move the pedal. So lesson is shift down early and keep a good cadence. I don't think there's anything wrong with the bike.
 
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