I agree with your opinion but an experienced team like Barcelona can surprise you at any time especially if they manage to maintain their top form next season. Xavi has managed his team and players very well, it has motivated all players to work optimally for the benefit of the team.
I believe Barcelona have less chance than Manchester City, Real Madrid, Bayern Munich and or maybe PSG, but Xavi has quality and he also has good squad depth to look forward to. Of course I can't fully expect Barcelona to appear in the Champions League final next season and win the title, but nothing is impossible.
So now Barcelona is trying to sign Joao Cancel, right? Actually it is insane how they manage the money for him, but anyhow they are trying to get him in. I can estimate if somehow they were able to sign him then the defensive lineup of barcelona will increase another level. Yes, you can say only one player is not able to change the whole team's capability to moon, but keep in mind Cancelo possesses the potential to exponentially enhance the stability and robustness of their defensive line. So Consequently, underestimating Barcelona would be a grave misjudgment. Barcelona is a good team, but I also agree the squad is not so good enough to say that they are definitely a contender for the Champions League titles.
Barcelona might not necessarily be the favorite to win the UEFA Champions League competition next season but I know that they'll surely be one of the strong contenders unlike many people think of them.
Looking at how well Barcelona manager Xavi Hernandez has groomed the team players since he took over, one can clearly see that he's made so much progress in finding the right style of football that matches the players and also know how to use the players. The addition of veteran player like IIkay Gundogan will further strengthen their sqaud and that's why I think that they'll do well in the competition next season