A dark spot on the bright sun stands for a flaw in something you admire, or a small shadow within a happy picture. It is read as accepting that even the brightest things are not spotless.
Does the traditional reading fit your dream, or did it mean something else to you?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.