Manual Color Changing
It takes at least a few cm of extrusion to purge the old color before switching to a new one due to mixing in the melt zone, and possibly much more depending on the particular pigments. If the old color is something bright like red and the new one is white or something close, it can even take many tens of cm before you get a clean new color.
Multi-color extrusion setups either use separate hotends per color or fancy retraction setups where each color can be retracted separately, along with purge towers. You cannot get a clean color switch in the print just by having one in the input filament, and this is probably why all the mixed color filament that's sold is blended - so customers don't get disappointed when it doesn't work like you expect.