This looks like normal leaf shed that evergreens experience in spring as new growth is emerging. Even though evergreen plants retain leaves for more than one year, the leaves do still have a finite life span, and after several years they shed. (As with deciduous trees, it's not uncommon for the foliage of some species to change colors before dropping.) Some evergreens, like pines, go through this process in autumn, but hollies do so in spring.

While leaf shed can also be a symptom of root health problems or pest/disease issues, we do not see signs of that here, as it would also likely be affecting the younger growth, a greater proportion of foliage, or causing entire stems to die back.

As long as they don't experience prolonged drought, Inkberry is quite amenable to a full sun exposure. If anything, this will promote a fuller, denser growth habit as the plant matures, though Inkberry never grows as densely as some other species used in landscaping (Japanese Holly, Chinese Holly, etc.). From what we can see, your holly looks to be in good condition.

Miri

You're welcome.