It is due to age? You can find many auctions of Man Tang Fu Ji porcelains in China from internet.However, I have no idea on Chinese porcelain and on this teapot. All information is from internet search and used for reference only. I do not have certificate and no return, sell as it.
Size (inch): Hight 8.5 (11.5 including handle), Diameter: 7.5. The item "Large 18C Chinese Qing Guangxu Blue-White Porcelain Teapot w Bronze Rim" is in sale since Wednesday, October 11, 2017. This item is in the category "Antiques\Asian Antiques\China\Teapots".
The seller is "jmikes_estate_sell" and is located in Saint Paul, Minnesota. This item can be shipped worldwide.