2020 Nissan Sentra SR on acceleration, loses power and revs high

I have a leased 2020 Nissan Sentra SR automatic brand new and 4 months later 8000 kms I was merging on the highway. I couldn’t accelerate although I had the gas pedal all the way down to the floor – no power but high revving.

I thought the gear shifted to neutral but still on drive. I coasted over to the shoulder and turned the car off. I took it into a Nissan Dealership and they gave me a rental and they asked me if I pressed the on/off button for 3 seconds? I told them no why would I press the on/off button while driving?

What could cause this?