John Mayer is a well-known Harmonizer, but he has doubts about the future of Fifth Harmony's success without Camila Cabello. The singer-songwriter shared an admittedly bizarre message via Instagram Live last night saying, "So I like Fifth Harmony, but then Camila Cabello left the band and now it's just this," he said, using a piano to demonstrate what four versus five notes played in a harmony sounds like.