For some reason the picture of the flag you mean appears to be not loading on my device right now, an Android phone running the medium Android App, so I am guessing it's the main US flag and not the confederates Dixie flag, that we might expect to be banned (Though it shouldn't be either, imho, live and let live, you know? ).
I've added the story to my lists to see if I can see later on PC, but it's interesting all the other pics in your story come up OK.