Gaga made a lot of mistakes over the last years in decisions and direction of her music career, but which one do you think it was the worst one or the one that made everything go downhill for her?
Wearing a different weird costume every single day. It made her one-dimensional, and she cycled through so many looks so fast that people have become bored with the whole thing. Now she's stuck with that image and if she ever tries to get rid of it, people will start abandoning her because she'd be going against her image.
Releasing Born This Way after her zenith TFM. I knew the general public wasn't going to sit well with it and with what she was spreading during that era.
I personally think BTW has amazing music and is a pretty good era, the GP didn't.
The only reasonable answer is Marry The Night. It started a domino effect. The timing wasn't right, the video was a mess, it didn't do her any favours and set her up for her worst era.