Doesn't work at all for me. I tried "pirate flag" and got something ugly and not at all piraty than was then made uglier and essentially blank by the background removal.
Yes I tried a few other prompt: from what I recall "syndicalist flag" gave a similar result, "hacker emblem" was refused as being potentially NSFW, and "anarchy" was the only one to give an actual result… of a cop emoji! Definitely not working well.