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: Brest was the better side by chances too.
Le Havre: −2.4 for the season (18 in the table). Brest: −4.8 (11). The gap between points and xPTS is built from matches like this one.