It is better to trust Brighton with the winning than giving it to Manchester United. Manchester United didn't conceive against Fulham and Brighton didn't conceive either against Everton. This is an indication that both teams are good defensively, judging by their games so far, so it would be best to play the bet under 2.5 goals. That's a more likely outcome, since both teams are boasting of a solid defense.
Manchester United are disappointing but I can neither go for Brighton. About under 2.5 goals bet, I do not think it is good to use just a single match to make such conclusion. At least, you should look for 3 to 5 matches between both clubs but the season has just started. I am not implying that you may not be right but a single match is not enough to make such conclusion. But if I still remember what happened in last season, it was hard to score more goals while playing with Manchester United.
Betting on under 2.5 is a very bold choice but according to the big odds we get and I also have to support this choice. We can also see that previously Man United were able to win against Fulham but at home Man United were only able to score 1 goal. Surely Ten Hag does not want to lose points in every match this season and Brighton who are currently at the top of the standings have great ambitions to defend so as not to concede. My prediction is that this match will only end 1-1 or 0-0.