Winemakers around the world use different fining agents to soften or reduce astringency/bitterness; remove proteins capable of haze formation, or reduce colour by the absorption of polymeric phenols and tannins. The fining agent reacts with wine components, chemically or physically, to form a new complex that can be separated from the wine.
Commonly used fining agents include gelatine, egg whites, and casein, none of which are vegan. Some countries have regulations about listing these items on their wine labels (Australia does list such items).
Therefore some of our wines would not be considered vegan if such fining agents have been used to clarify.