small vibration/shaking when the indicator panel hit 1-2 bar above EV mode

Hi team

I recently bought a 2016 Aqua (lower specs version of Prius C). It has driven 70K/43 miles, I notices that whenever the indicator hit about 1-2 bar above EV range, I can feel a little vibration/shaking from the engin. It can happen between 60-90K/35-55miles, but it's most noticeable around 70-80K/45-50miles.

It looks like this:

Is that normal?

I have searched the forum, some post says its normal, but most posts can't seem to find a fix for it.