Some people may think that Hua Fei was so favored by the emperor only because his brother Nian Gengyao had great power at that time, so he didn't take any other concubines seriously at all, and even abused and fought some concubines that the emperor liked. The emperor naturally doesn't like ruthless people, and because her brother was later changed and died in prison, she was really left out by the emperor.
Others said that the Hua Fei, as we know it, actually didn't live long, but she was given such a long role performance because of the plot of the TV series. In reality, she died a long time ago, and there are not so many stories in TV series, just paving the way for the plot and characters.
According to the story of Hua Fei's later death, I think she was greatly favored at first, but later she died in limbo because of her younger brother Nian Gengyao. At first, because of Nian Gengyao's high position, he did a lot of things for the emperor and made a lot of contributions to the country, so the emperor doted on Hua Fei. Later, Nian Gengyao was killed by the emperor because of his high position. At this time, he must be tired of Hua Fei.