The score says how it ended. xG says how it should have ended: it is the sum of the chances each shot was worth, not an opinion about the game.
The score matched the game: Troyes was the better side by chances too.
Lorient: −1.4 for the season (12 in the table). Troyes: +0.1 (16). The gap between points and xPTS is built from matches like this one.