If the game score is 7 to 7 and a player plays Invert Timelines, while none of the players have more than 3 cards in the deck, who wins? And is it relevant if one person has 2 and the other has 3 cards in deck?

The player who did not play Invert Timelines wins the game.

According to the official ruling for this specific scenario:

1. Simultaneous Actions: Invert Timelines forces both players to discard and draw simultaneously.
2. Turn Order: When actions are simultaneous, turn order is used to determine the sequence of resolution. The active player (the one who played the spell) resolves their discard and draw first.
3. Deck Depletion: The player who played Invert Timelines attempts to draw 4 cards. Since they have 3 or fewer cards in their deck, they fail to draw the required amount and lose the game immediately.
4. Winning: Because the active player loses during their resolution, the game ends before the opponent ever attempts to resolve their own draw.

Is the deck count (2 vs 3) relevant? No. As long as both players have fewer than 4 cards (the amount required to be drawn), the result is the same. The player whose turn it is (the one who played the spell) will always be the first to attempt the draw and will lose before the other player's deck size matters.