Huge gap between under the caroussel on iphone

### Describe the bug:

I am getting an issue on the iphone mobile version however . (Firefox on IOS 12)

There is a huge gap between the images and the thumbnails line of smaller images. If there is no thumbnail images, the gap is before the next element.

This gap is not happening on the desktop version.

My settings are :

Size L
Gutter 5
Height 400 px
Remove bottom spacing

### To reproduce:
Please check https://www.filmlabs.org/technical-section/film/

### Expected behavior:
There should be no gap, like an Android.

### Screenshots:

### Isolating the problem:

- [ ] This bug happens with no other plugins activated
- [ ] This bug happens with a default WordPress theme active
- [ ] This bug happens **without** the Gutenberg plugin active
- [ ] I can reproduce this bug consistently using the steps above

### WordPress version:
5.7.3

### Gutenberg version: