The view finder image may become unclear and hazy when shooting under direct sunlight. This may occur when erroneous light finds its way into the viewfinder caused by light reflected from surface of the eyelid or eye. It can happen if you are not holding the viewfinder close enough to your eye. If the camera features a detachable eye cup, make sure that the eyepiece cup is attached to the view finder to avoid irregular reflection. The reflected light may also come into view finder from a gap between the eyecup and eyelid if you shoot wearing eye glasses.
To resolve the issue, try to cover the upper part of the viewfinder with your hand or wear a cap to prevent sunlight from entering the viewfinder optics of the camera.