A flag lowered halfway is read as public mourning, or a lowered spirit. Dream books link it to grief shared by a community, and to pride or energy that has dipped for a while.
When this appeared in your dream, what were you feeling?
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.