Is z-index necessary on .swiper and .swiper-wrapper?

[markedwards]

The .swiper and .swiper-wrapper classes have z-index: 1 on them, which messes with the stacking order of the surrounding layout. What is the reason for these declarations?

I end up wrapping the swiper elements in an isolation: isolate to deal with it, but it seems like these declarations could be removed so the elements would not interfere with the normal stacking order.