>>11156895>>11163343From a different angle to show that it's not the shadow from the wing.
Full disclosure, though! I had this valk on a shelf in a room that got sunlight, but there was not direct sunlight on the valk. It was on the shelf for several years, with periodic dusting and whooshing missions. Nonetheless, it's just the side facing outwards that yellowed; the leg on the opposite side is still fine. So it's definitely due to the sun and you may be able to prevent the issue if you're careful.
Still though, I had both the 1/48 Low-Vis and the Arcadia VF-1J on the same shelf and neither show any signs of yellowing. For the VF-1J, Arcadia's white plastic has a very slight pinkish hue to it, so I wonder if that helped prevent it from yellowing like the Yamato with it's pure, vibrant white.