not always hide columns on mobile devices

i have set 6 column and hide last one for all devices to use 5 columns in row for desktop works ok but on mobile it keeps size of 6ht column but in code there is

so it should not be visible and should hide also its space

I found out that on responsive css there is line like this

@media (max-width: 1280px)
.column-wrapper .ba-grid-column-wrapper {
flex-grow: 0;
}

why??