Barcelona defeat to Paris Saint Germaine on Tuesday that ensured their exit from the UEFA Champions League competition came as a huge shock to them as a club and because of the effects of the shock coupled with how they claimed the defeat was aided by the referees harsh decisions, I don't think they've fully recovered from the result of the game so I think it'll definitely affect them when they travel to the Santiago Bernabeu to face league leaders Real Madrid on Sunday.
Real Madrid on the other hand played over 120 minutes in their game against Manchester City on Wednesday but came out victorious in their own game and have progressed to the semi finals of the competition. Against Barcelona on Sunday, I expect Real Madrid to get all maximum three points from that game or at least get a draw. I don't think it'll be possible for Barcelona to get a draw in that game.
With their match being so poor that there could be red cards for Barcelona players, it was surprising, even though in their previous match Barcelona were one goal ahead of PSG, but PSG were able to turn things around even more than the results of their previous match. I think that Barcelona winning the previous match could make them more confident that they can win again in the second leg, but in fact PSG could make them lose, which might make Barcelona's mentality drop.
I think this defeat is tough for Barcelona and what you say is true, perhaps this could have an impact on Barcelona's next game which will be against a strong team that is in first place in the standings. considering that Real Madrid is also a strong team this season with their points far ahead of other teams. and with Barcelona's defeat to PSG, I doubt that Barcelona can win and even to match it, I don't think it's possible. but no one knows whether Barcelona will surprise them or not in their upcoming match.