The current condition is that Barcelona are being linked with Messi besides that they also need fresh funds of more than 170 million to balance their cash balance which is indeed something like this that is most likely to be obtained from the sale of several players.
Even though there have been a few added to the current list for sale but that will not be closed and one possibility is to sell a player like De Jong for that. And when they want Messi now, the possibility of releasing Gavi can still happen, I think, although it's not really worth it to let go of a young player who has very good prospects.
Before rumors of Messi being linked back to Barcelona. some rumors have reported, that Barcelona will sell some of its players. yes, it's not just De Jong who is always rumored. but there are several other names such as Ansu Fati, Ferran Torres, and even rumors that Raphinha is also on the sale list in the next summer transfer window. no exception, with several of their senior players Segio Reberto and Jordi Alba also on the list of players to be sold. but, so far everything is just rumors and we don't even know what the Barcelona management will do later.
Speaking of Messi, this kick he always makes hot news regarding his return to Barcelona. No less interesting, Al Hilal, a club from the Saudi Pro League, also made a fantastic offer. but, there was no clarification whatsoever from Messi's side. in fact, the news always links Messi to Barcelona.
For Gavi, I'm not too sure that Barcelona will actually let him go. although there are many rumors linking him to several big European clubs, he is a player who has become a long-term project for Xavi and Barcelona. so, let's wait for further news regarding gossip from Messi and Barcelona players.