Chelsea claimed that they are not fighting for the Premier League this season, but among the top 4 which they're hoping to finish will be difficult for Maresca to secure this season. However, Brighton enjoy anytime they play against Chelsea, after they humiliated Chelsea in the FA Cup, they still did the same thing to beat Chelsea 3:0 in the Premier League.
Chelsea failed to have a single shots on target, this is the first time I can see Chelsea played a match without having a single shots on target. They still have 14 more matches to play before the season should end, maybe they can still strengthen their position with the rest of the games.
Perhaps you missed the scene where Brighton fans were chanting at Chelsea "can we play you every week?"

That was very ridiculous of Chelsea allowing Brighton to humiliate them twice within a week. I think for the past two years now, Chelsea haven't played any game without having a single shot on target for the whole of ninety minutes. That's very pathetic indeed. We understand it's normal to lose a game but it's absolutely abnormal for Chelsea not to have a shot on goal against Brighton. Obviously, their chances of finishing in the top four is not longer certain and likewise, winning the conference league is not guaranteed too unless they improve their game.