Which music group's 1990 Grammy Award was revoked after a lip-synching controversy?

The music group Milli Vanilli had their 1990 Grammy Award revoked following a lip-synching controversy. The duo was found to have not sung on their album, which led to a significant scandal when it was revealed that they had used studio vocalists instead. As a result, the Recording Academy stripped them of the Grammy for Best New Artist, marking a rare instance in Grammy history.