It was an observation based on a lip sync comment made by silent jonny, and — yes — the fact that J-Lo as everyone knows cannot sing worth a lick.
I think the contestants are aware of that too.
In fairness to J-Lo, I didn’t say she lip-synched. She sings her own songs, yes ... it’s just that her voice has to go through some NASA approved process before it can be digested by our ears :-D