The direct light from the Sun is yellowish, because the blue light of the sky is subtracted from it.

If the sky is covered with clouds, then the light is white, because the blue sky light is mixed again with the direct Sun light.

If the sky is clear and there is an unobstructed view of it, the light reflected by a white object will be the sum of the light coming from the sky to the object and directly from the Sun to the object, so it will be white. For example this is true for white clouds and white snow.

This, i.e. that the Sun outside the atmosphere is perfectly white, has been understood for a long time, since the 19th century.