In America (USA) "Soybean Oil" is the most common vegetable oil that everything is cooked in. How common is it in Poland - and more importantly: How easy is it to avoid Soybean Oil in Poland?
It's available, but very easy to avoid it, other types are much more popular, I don't think I've ever even used soybean oil. It's "olej sojowy" in Polish, so just avoid any label that says that.
I think the most common is sunflower oil or using lard instead of oil. Restaurants may use palm oil to save on costs.