Lewandowski is still the best striker, but he is old. In my opinion, it is better for Barcelona to sell him because he still has high value because by selling Lewandowski, Barcelona has the capital to buy other players. Moreover, currently Barcelona is still having financial difficulties buying new players to strengthen the squad next season.
Lewndowski is still a good striker. He was able to make 18 goals for the season. Indeed, he is not young anymore, he is 35 years old. Maybe for a lot of running he's not what he used to be, but for finishing he's still pretty good. Selling him is a good option if Barcelona already have another replacement. But hold for 1 year next season I think is also good. Lewandowski is in the top 5 scorers this season.
1. Alexander Sørloth 23 goals
2. Artem Dovbyk 21 goals
3. Jude Bellingham 19 goals
4. Robert Lewandowski 18 goals
5. Antoine Griezmann 16 goals
Source:
https://www.espn.com/soccer/stats/_/league/ESP.1/view/scoringIf Lewandowski is retained even for just one season, I don't think it's a good decision. Because after all, if Barcelona still needs money then of course selling Lewandowski to the Saudi league could provide good profits too. Unless, for example, Lewandowski intends to retire at the end of next season then it might not be a problem, because it is possible that Lewandowski will give all his abilities in his final season for Barcelona. But indeed, considering that Lewandowski's contract is still long until 2026 then of course, Barcelona must also respect his contract. Thus, I think Barcelona is making a mistake again, because signing old players for a long period of time is not worth it, especially because Lewandowski is a forward who needs speed.