Save for web scales down resolution even tho slices are under the max. resolution

If a file is over the “Save for web” maximum resolution of 8192px it scales down the image to max res. Even though exporting slices that are smaller than the max. res. (1080x1350px) it still scales it down to about 75%. The original file is 10800x1350px big, and has 10 slices á 1080x1350px that are scaled down to a height of 1024px.