What is the reason for blocks sliding on ipad?

Question

css

There is a layout at kamin-premium.ru
Positioning blocks on flex. Prefixes for safari are affixed. But layout floats on iPad Air tablets.
Testing through www.browserstack.com service
Specific problems: The "Top Sellers" section is placed in one column, although it should be in 2. The "buy" button fell apart there. Section "All for the fireplace" - galloped down one block.
At the same resolution, everything is correct in other browsers.
If it's not difficult, poke what my mistake is.