Product Thumbnails to 2 columns

Use these codes to the Custom CSS box

Desktop Only

/* Desktop Only */
@media screen and (min-width:992px) {
.ProductItem-gallery-slides {
    display: grid;
    grid-template-columns: repeat(2,1fr);
    grid-gap: 5px 5px;
}
.ProductItem-gallery-slides:before {
    display: none;
}
}

All devices

/* All devices */
.ProductItem-gallery-slides {
    display: grid;
    grid-template-columns: repeat(2,1fr);
    grid-gap: 5px 5px;
}
.ProductItem-gallery-slides:before {
    display: none;
}

Result