Did you see the picture in the post that was quoted?
It shows as rooted and knox efuse intact. So the warranty would still be good as long as it doesn't trip the efuse.
Look at the picture before telling me a generic answer. I already know that when the excuse is blown the warranty is lost. How do they have root without tripping the efuse?
the picture is a false negative.. magisk uses resetprop to change prop valuescon devices to try and "trick" apps that check for certain props by setting it to 0x0 on boot..
basically knox is still tripped but visually magisk itself makes it appear normal