I have to admit that I was quite shocked by her performance. I think most people know that she is not the greatest singer on the planet, but that was astonishingly bad.
We wondered if:
a) her In-Ear failed completely (but then she probably would have pulled it out?)
b) they broadcasted her live mic by mistake when they should have switched the playback track back on?
I guess the private sponsor, who paid more around 1.5 million USD for her appearance there, was not too happy about the result...
Almost 30 years ago Madonna appeared on an awards show and sang poorly. She received a "tongue in cheek" award from we minions: The "Living Proof Nile Rogers is a Studio Genius Award". Her live singing was notable for the contrast with the polished album recordings.
Nothing new, back in the days of the Hollywood movie musicals it was common to replace the actor/actress vocal with studio performer - Marni Nixon replaced famous actresses in West Side Story, The King and I, My Fair Lady, etc. Perhaps it's time for Madonna to find a Marni Nixon (she passed away 3 or 4 years ago, one of the most heard but unrecognized voices in the media).