FDJ has a contract with Barcelona that expires 2026, with a total value of around €112m remaining in salary. Its that high because he agreed to a greatly reduced salary during the pandemic, on the condition that the reduced salary would then be added to his contract (which was already gigantic since then Barcelona club president Bartomeu had no clue what he was doing, he is the main reason they are in the financial crisis they are) during the remaining part of it after the pandemic.
This means his weekly salary today is around 40-50% higher than our highest earner KDB. Meaning that if he would come here this summer on the same salary as our highest earner (which he is probably not worth, but thats another discussion) he would have to give up around €40m worth of salary (in total) that he would otherwise get if he just stays at Barcelona. What was said last summer is that he has no intention of doing that, especially not considering a major reason the salary is as high as it is because of his own good will against the club by agreeing a reduced salary during the pandemic in the first place. And if so he wants Barcelona to compensate him for the money he would lose by going to another club, since no (European) club would offer him anything close to what he earns today. Barcelona on the other hand has no intention of paying him €40m in compensation if they sell him, the whole reason they want to sell him is because they dont want to pay him that money.
I might have got some details or numbers wrong so consider this as a broad explanation rather than a 100% factual one. Its either way a complicated situation with his contract. Barcelona only wants to move him because of his contract. FDJ doesnt wanna give up €112m worth of salary. No other club is willing to pay him that much. My guess is that he is staying at least one more year in Barcelona.