I've only seen clips of this (too cringey to watch the entire thing) but from what I'm reading, her earpiece was knocked off/stopped working and she couldn't hear herself over the noise, which is why she sounded like shyt whenever she tried to sing.
For God's sake someone PLEASE tell me that's all there was to it. I really don't wanna give Mariah no epic L first thing in 2017.....
If it was just a sound issue then surely people will forgive her......
EDIT: Jesus Christ.......I just read a post somewhere else saying this dwarfs the Ashlee Simpson incident