Never done whip-it’s before, if they said they are a 20 second head high how could someone tell after? I worked in/around a couple kitchens when I was younger and they are usually full of drugs. I knew there was at least weed, cocaine, and mushrooms available on one of them, the other I think was weed and meth, cocaine I think was yo costly for the people who worked there.
That said, D) they shouldn’t be a manager of anyone if they think inspiring people to do better is threatening the entire staff with no raises because of a that. Just say something one time and be done with it if you don’t know who it is. If you pay well and are respected, someone would be telling you who it was because they are sick of their shit.