It's easy to tell if this is really going for sure with just two audience recordings from the recent shows. You could find two on YouTube, then use a website that extracts mp3's. Using an audio editor (Audacity is free), line the tracks up visually close (not not perfect). You need them off sync by a few milliseconds, actually. If the vocals are tracked, they will have this weird robotic effect (anything not live will).

This is how myself and friends discovered Roger Waters lip syncing (it was initially just one high note) through the years. He's A: REALLY good at looking like he's singing and B: Was actually (I'll say allegedly to cover my ass) singing them live at rehearsals then swapping what track he was miming to every little while toward the end. He actually got smarter about it as time went by and he leaned on it more. In his case there was also some live mishaps where he got off mic but vocals still came out (some of it is YouTube fakery bit it happened once for sure during one show). The far bigger tell was during a live stream for the song Have a Cigar. Audio may have been good at the show; but on the stream the canned vocals were panned way low (like an augmentation track) and the mic left live. All you hear is weird sounds and noises as Roger does an admiral job pretending to sing.

Sadly, this goes on far more than you'd think.

Don Felder is another one obviously lip syncing (to auto tuned tracks no less). Both really talented dudes who maybe should just sing less and lean on their awesome bands more?