On mobile zooming slows or accelerates panning speed

Nobody has claimed this yet.

**mapbox-gl-js version**: 2.1.1

**browser**:
- iOS 14.4.1 Safari
- Android 9 Chrome 89.0

### Steps to Trigger Behavior

1. Open https://docs.mapbox.com/mapbox-gl-js/api/ in your mobile browser and scroll to the example map
2. zoom in or out with two fingers
2. while zooming pan up or down to move the map

### Expected Behavior

- Panning while Zoom in: the panning speed accelerates and the map is moving really fast
- Panning while Zoom out: the panning speed slows down and the map is moving really slow

### Actual Behavior

- panning speed (map moving speed) is the same like without zooming at the specific zooming level

Start by reproducing the gesture on the API example at https://docs.mapbox.com/mapbox-gl-js/api/ using mobile Safari and Chrome. Compare panning during pinch zoom with panning alone, and resolve the contradiction between the title, expected behavior, and actual behavior before identifying the relevant gesture-handling entry point. Done means the intended panning speed is consistent with the clarified behavior.

Written by the indexing model from the issue text.