Yes, Lewandowski is indeed an old star, even though currently his performance is not as fast as before, but we still cannot forget the digital footprint he made during his time at Bayern Munich and even at Barcelona, he is also a striker that can be relied on, even though he is not as fast as when he was is at Bayern Munich but at least he is still an important player for Barcelona and Barcelona will have difficulty competing in all competitions if Lewandowski leaves Barcelona before this club has a player who can replace Lewandowski with better performance and Barcelona will also have to dig deep into their pockets if want a quality striker from a top club.
It looks like Lewandowski will remain Barcelona mainstay next season even though he is getting older, his experience is really needed by Barcelona, which currently relies more on young players. He can still be relied on on the front lines even though his goal productivity has dropped drastically this season, Barcelona will not let Lewandowski go before finding a suitable replacement to fill his position.
He managed to score 18 in La Liga this season, this record is not too bad for a player his age. You can't compare when he was still defending Bayern Munich, at that time he was still at the peak of his performance and he was younger than he is now. Barcelona must retain Lewandowski to fill the front line due to the financial limitations they currently have. The only option Barcelona can do to strengthen their squad is by selling other players to bring in other quality players so that their front line becomes sharper.
Lewandowski's goal productivity this season has not decreased too much, he is still able to score more than 20 goals in a season in all competitions even though so far Lewandowski has only scored 18 goals in 34 appearances in La Liga. Lewandowski's goal productivity decreased because he was injured and had difficulty finding his best form, but Lewandowski still proved himself as a productive center forward even though he was still inferior to Alexander Sørloth and Artem Dovbyk.
I think Barcelona will still make Lewandowski their main center forward next season even though he is turning 36 years old. Lewandowski is an experienced center forward and he can still be relied on, but Barcelona must immediately find a replacement because the time will come for Lewandowski to leave due to losing competition due to aging.