I'm growing some capsicum baccatum chili in pots on my well-lit balcony, and they have grown very well, producing plenty of fruits. The leaves are healthy, with no marks of any kind. However, I've noticed that virtually all of the fruits, some time after they grow, begin to form some smudges:
As the second photo – right above – shows, these smudges eventually propagate, covering much of the fruit in a semi-even fashion.
I'm very inexperienced with chili (this is literally the first time I'm growing any), so at first I thought it was part of the natural process of changing color. But it just doesn't feel normal. I also wondered whether these are sun burns, but as the photos might reveal, the plants are behind a frosted balcony window, diffusing the sunlight.
I've tried to find information online, but none of the conditions/pests seem to match this. I also consulted questions such as this one and this one, but they don't seem relevant to my issue.
Any ideas what this could be?