At Control Magic, here is how we define Standard, Modern, and Vintage Cards.
Vintage decks may consist of cards from all Magic card sets, plus the following cards: Sewers of Estark, Mana Crypt, Windseeker Centaur, and Nalathni Dragon.
Standard decks may consist of cards from recently released Magic sets (roughly the last 2 years). Currently those sets are: Kaldheim, Zendikar Rising, Core 2021, Ikoria Lair of Behemoths, Theros Beyond Death, and Throne of Eldraine.
Modern decks may consist of cards from Magic card sets going back to Core Set Eight and Mirrodin in 2003 through today.
Source: Wizards of the Coast