I don't remember there being a flag like this for some time (but then again, I haven't flagged a question as being off-topic for some time also). Searching MSE, MSO and here didn't turn up any meaningful results. The help page is vague in this aspect. I then ask:
- What is the "blatantly off-topic" flag? What is is worth for?
- How is it handled differently than the other flags?