Raktajino... has liquor in it?

I like coffee. I like Star Trek.

I've had a mild interest in the raktajino, a Klingon coffee drink commonly consumed in DS9. I've looked up a few fan theories and fan recipes. I haven't seen any references to a canonical recipe, so I get that there's a bit of fun and personal preference involved.

The only thing I don't understand is why raktajino is commonly claimed to be made with liquor. On the one hand, I understand why Klingons might want a stiff additive to their caffeine. However, the context in which characters on DS9 drink it does not suggest the presence of intoxicants. I recall at least a few occasions in which bridge officers, while on duty, drink a raktajino. Surely even synthol is not OK when you're on shift for Starfleet.