What is in Limoncello that makes you way drunk?

So I’m a regular drinker, 1-2 times a week for decades, who drinks mostly rum and cola or vodka and cola, or margaritas. I will often drink any array of alcohols, beer, etc, without issue. I only drink to a buzz as I find anything beyond that unpleasant. In Italy last week I had two ‘Sorrentos’ which are Limoncello/champagne/mint leaves. I was near hammered, slightly slurring speech and all. Tried two more on a different night from a different restaurant. Same effect. Tried two more here in the US…..SAME EFFECT! There must be something going on here…. some chemical in the lemons?