Is this a red flag?

I am a very qualified and experienced bartender and server. I have been in restaurant mgt for a while and have decided to go back because I’m just not making enough money and the company that I work for has changed so much that it’s not the same job anymore. I have 10 interviews scheduled so I know I will get multiple offers. I need to be sure that I will make enough money so when I ask questions during the interviews one of the ones I ask is “what are your average weekly sales?” With my experience I know how much I’d be making based on the answer to this question. No one had an issue answering this except for this one manager. His response was “can’t discuss that” and I was taken aback and made a little uncomfortable by this response. I didn’t get good vibes from him anyway but I also interviewed with a different restaurant that’s owned by the same people and the managers at that interview were amazing. I have done a tiny bit of googling but I’m still unsure. I don’t think it’s too forward of a question to ask. I am qualified enough to know that I would be great at the job and I am always a valuable employee wherever I work. I should be able to gage how much money I would be making so I can decide which offer to accept. Thanks in advance.