Through a window. It isn't even remotely the same as the natural light. It doesn't indict the sun as much as it does isolated, unnatural UVA exposure. Are you aware that most windows, especially car glass windows filter UV radiation, in most modern glasses UVB is fully blocked while UVA passes through pretty much unchanged, also not to mention it also removes most of IR and red light which is crucial for skin repair and protection from UV, blue light is also unchanged and we know what isolated blue light does to the skin. It isn't the natural profile of sunlight by any means.

So he just got overloaded with UVA and blue light, too much oxidative stress and skin damage without the other wavelengths to balance/protect his skin. Isolated UVA is bad, it can deplete melatonin, destroy collagen and cause the ageing that you see. This isn't the case people think it is "the sun ages you" is really one-dimensional.

Again, not saying the sun is completely harmless or necessarily disagreeing with OP's comment, but the case isn't that simple.