Sediment in pre-mixed vodka cocktail!?

I poured a can of vodka iced tea lemonade out into a glass and there was dark sediment🥀🥀 I contacted the company with pictures and they said it was a ‘protein haze darkened by tannins in the tea.’ Where tf is the protein coming from 🤨

Does anyone have any knowledge on this lol please and thank you in advance 🙏