It's either, depending on what language you speak. You wouldn't deny English speakers using "Cologne", "Munich" or "Bavaria", would you? (Köln, München and Bayern FYI)

Besides, at the time that this photo was taken, the city's population had been largely german for hundreds of years. I don't know the exact date but it's gotta be late March or April '45. There's a T-34 in the background of another picture so it is debatable whether the city belonged to the Reich (de jure), the Soviets (de facto) or Poland (geographically) at that point. But I wouldn't categorically deny it the name Danzig.