2017 Corolla engine problem

Hi guys,

My wife bought the 2017 corolla accent in June last year.
From about April this year, some problems have been happening which the speed suddenly going down and maximum speed to 40km with high RPM when she accelerates.
It doesn’t stop until she stops the car and re engine on. She took even below video(photo for this forum) as the evidence.
It happens very suddenly but not often, once a month approximately.
I talked to the Toyota service center but they told me after watching the video that it always happens and there is no problem which is CVT engine’s feature. They asked me to take a car and demonstrate it. It happens suddenly and not always which I can’t demonstrate it unless otherwise accidently and fortunately happens when they are with me.
Just want you guys to give me any advice or technical opinion about this problem.
Thank you. 559C0EAD-819D-4133-9C86-EE46D28B5CD2.png