I think there are a lot of extremes suggested here and a lot of conspiracy theories.
I don't think Messi was kept in the dark, and I don't think there was a bomb with the audit that took everyone by surprise. Let's be realistic here, we're talking about a huge club and the richest player on the planet.
I think the truth is somewhere in the middle. Laporta took over and his administration got to work. After they had time to analyze the financial ruin with full access, they realized just how bad it was and obviously at that point they'd have known what it would take to keep Messi, and I think they told Messi's entourage. There's no reason not to, for the following reasons: 1. Messi would have to be told why he's supposed to halve his wage and 2. imagine the fallout if they keep it a secret, the renewal doesn't happen and Messi blasts Laporta's administration for leading him on. It just isn't reasonable that Messi wouldn't be told what the situation was.
This is where two very logical things start to happen - on one side, Barça tries to offload deadweight, and on the other side Messi's entourage begins engineering a move to a different club, knowing that Barça likely won't succeed in moving said deadweight. Barça kept players in the shopping window the entire Summer and you could see that we were moving from one player to another. Umtiti, Coutinho, Dembele, Griezmann, Alba... names were leaked one by one as the club was trying to put pressure on the players to leave. Unsurprisingly, no one wanted to leave because they were on fat contracts that couldn't be replicated at clubs not run by incompetent criminals like Bartomeu. So, we couldn't move any players because they were too comfortable with their contracts and more than willing to force Barça into paying them until their contracts run down. These players were first and foremost thinking about their own bottom line, not about Messi's wishes or Barça's priorities. This was expected, and in the end we spent most of the Summer and the entire EURO unable to move anyone on. I think our hopes ended with Dembele's injury and it became clear we wouldn't be able to make the money necessary to finance Messi's new deal.
During this time, Messi prepared for the likely outcome that people like Sergi Roberto, Coutinho, Umtiti etc. would be too comfortable to leave and he wouldn't be able to have his contract registered, even with a 50% wage cut, which is the most he could accept under Spanish law. I mean, why is there a conspiracy theory here? If you told me all these details before the Summer started, I would have lost all hope of retaining Messi. As soon as Bartomeu gave deadweight players huge wages, this was done. Slow train coming.
So, I don't think Laporta or Messi were taken by surprise. They knew what was happening and I do believe the Club tried to shift dead wood, while Messi held out hope, but I think ultimately both expected this outcome as it could only have been avoided if the Club somehow managed to sell nearly useless players for a lot of money. It didn't happen, the time to join pre-season came and the Club and Messi decided to come out with the "news" in order for Messi to have enough time to sign the deal with his new club, as the Ligue 1 already started. So, no conspiracy really, they just ran out of time and options and couldn't wait anymore.
There is a difference between all of this being pre-arranged months ago, and being planned for months ago. Difference being whether an outcome was a contingecy or the only course of action. The reason I don't think it was pre-arranged is the fact Barça signed Kun. That wasn't an obvious transfer and now we have problems registering the player. That should tell you it wasn't pre-arranged because if it was, it would mean Messi allowed Kun to join Barça thinking he'd play with Messi, all the while Messi knowing it would never happen. That's far-fetched as Kun could have joined any other club and Messi could have just told him in private not to sign for Barça because of him as he'd be gone.
About Laporta, he is certainly capable of making a show and he's a politician, so it is not above (or beneath) him to campaign on Messi's renewal, to then bin that option while still acting like there's a lot of effort to make it all happen like he promised. So no, I'm not oblivious to Joan Laporta, I just don't see the interest for him to ditch Messi. Certainly it is beneficial for Barça to keep Messi instead of Coutinho, Dembele, Umtiti etc. This is simple common sense, like you'd prefer to eat a sandwich instead of a turd, so I think he tried but couldn't make it happen, because you know, math and contracts and all that.
This is already long. To conclude, I think Messi wanted to stay but couldn't. I think Laporta tried to keep him but couldn't. Barça wanted to get rid of deadweight but couldn't. Ask yourself this: if you were a useless player like Umtiti, would you accept a contract with a smaller club for one-fifth of your Barça wage? If you were Laporta, would you be able to find a way to force a player to ditch his fat contract? If the answer to both those questions is no, then you don't need a conspiracy to explain what happened here, it's just individual interests that combined in a way that has us screwed.
About Messi's departure, I knew it was coming, I'm just sad it happened this way. I hoped Messi would be able to say "This is my last season" and we'd be able to actually honor and appreciate that fact. I hoped to be able to watch his last Clasico, knowing it was his last. I hoped to be able to watch his last Camp Nou game, knowing it was his goodbye. My sister now lives in Barcelona so I held out hope that we'd be able to hang onto Leo for one more season so I could have a season's worth of time to plan out a trip after 'rona to see him one more time in a Barça shirt. I saw him live once, I hoped to be able to do it for a second time in our shirt, but now that won't happen. I feel like after everything Messi's given me and my family and all the joy we had watching him, the proper way to pay homage would be to see him live once more. Now I'm going to have to go to Paris to say my goodbye. FFS.
I hope Messi wins the Champions League with PSG. He's going to enjoy it there, as he should.
God damn it.