Here's a list compiled by forum members.
Cinnamon is definitely one of those that are abrasive to polycarbonate
tanks. I'm not so sure about minty flavors, I think it depends on the flavorings used and the amount of oils or acids present that causes the etching on plastic. If you're worried about harming your tank, you could look into the Kanger ProTank. Only 20 bucks, made of pyrex, and the heads are easily replaceable and rebuildable as well. Good luck!