If you compare the photos in the linked article from 2016 with the photo of the same area in the current photo posted in this thread, you will see that someone decided to clean off that brown rust seen in the earlier photo, and that cleaning also took off the original blue that was in that area.
This is a good example the results of choices made about cleaning or changing an antique that has some areas that look bad - is it better to leave it alone, or to clean it some!
That's the classic collector's choice.
View attachment 508047
View attachment 508048
View attachment 508049