Hello Artem Temos, I am facing one more issue with the mega menu. Megamenu is not responsive in some pcs its shows all menus and social icons but in some pcs it doesn’t show the social icons. Kindly check the below attachment to get the better idea.
Yes, it is correct, since there are a lot of menu items in your categories menu you can’t see it in full on small screens. It is not something that can be fixed with CSS. You would need to reduce the number of menu items there if you want to fit small screen sizes like on your example.