Lady Gaga's fame as a musician went down because, frankly, what goes up...yup, must come down. It's not at all unusual for a singer's popularity to rise and fall. She is still an awesome singer with a crazy huge fan base. The fans she has are devoted so they don't seem to mind if she's not the hottest item at the present. They are still in love with her.
In a world where no singer or celebrity is safe, everyone's status will fade at times. Lady Gaga doesn't seem to mind that her popularity as a female musician isn't at its peak. She has a great movie out, A Star is Born, and that has been her focus for a while. Lady Gaga is multi-talented. So, although her popularity isn't up to what it used to be, it's still enough for those who love her most.