Thank you for sending us your accesses.
1/ https://prnt.sc/52aZ0C9gIM1A – What is wrong with the quick view?
2/ I can select variation – https://prnt.sc/LavHnO7_-DgO https://prnt.sc/wokaqMw_AOYT
3/ https://prnt.sc/_7dKPopuOHG- – single product page is fine.
4/ AMP plugin is activated. If you do not like the AMP view on mobile, just disable XStore AMP plugin. https://xstore.helpscoutdocs.com/category/112-amp-plugin
It looks like, you just need to clear cache of your browser and problems will disappear.