The results show something more than subtle.
What you’re going to see in our screenshots and videos are a variety of results, sometimes indistinguishable, and other times enough difference present to raise an eyebrow. When playing at 60 FPS without the lock enabled, you will encounter shadows with high aliasing (blocky edges), and sometimes even shadows missing altogether. With the 30 FPS lock enabled, the edges of shadows are much smoother, and shadows will appear on certain surfaces.
In my opinion, I think Naughty Dog wanted to incorporate the higher quality shadows by default, but simply couldn’t get the game to run smoothly enough, opting to lower the intensity of shadow quality when running at 60 FPS. After all, in the case of PC games shadows are usually the first thing to go when performance takes a dive.
During my playtime with the 30 FPS lock disabled, I didn’t necessarily notice the blocky shadows during gameplay. The only occasions where they caught my attention is when I was looking for them, or a shadow was flickering (uncommon).