The singer spoke about the "rock bottom" moment that the photo documented in her 2020 memoir.
The two blonde pop stars rose to fame around the same time in the late 1990s and early 2000s.
The singer said her three children find the criticisms “confusing".
Having already met Ariana Grande, the Causeway star admitted there was one surprising star that would "knock me over" if they crossed paths.
"I didn’t respect my own power," the singer and fashion mogul wrote of the image, taken in 2017.
Is it safe for children under 16 to use hair dye? We asked an expert.
We definitely didn't see that one coming.