Now that all three trades have chimed in with their own behind-the-scenes takes, after reading all of them this is how I think things went down:
1.) At some point this year, Sony and Marvel sat down to start renegotiate their deal. It was always gonna end after Far From Home, and there would have been no rush to do it before now.
2.) Disney starts by asking for half of the profits as a co-production with co-financing, and Sony starts by offering 5% without co-financing. This is basically what the Deadline article says. Through negotiations, we get to the point where Disney has come down from 50% to 30% (as per THR) and Sony has agreed to co-financing and gone as high as 25% (as per Variety).
3.) At this point, they're close enough to start talking about other things. Things like the fact that Sony really wants to do a Holland/Hardy movie somehow (whether it's officially a Venom movie or a Spidey movie probably doesn't matter to them). Like bringing on Feige to help with the spin-offs. Like Disney probably wanting Sony to slow down on said spin-offs so as not to fuck up the brand, and wanting to get a cut from said spin-offs that do happen.
4.) At some point over the last 2 months, Disney walked away from negotiations. Variety is very clear on this, and the other two trades don't contradict them. Deadline did at first when they broke the story and said that Sony never responded to the first 50/50 offer, but they went back and stealth edited that out of the story. What we don't know is why Disney walked. Variety offers up that it might just have been about the money, or it might have been because after Dark Phoenix bombed, one of the people above Feige at Disney wanted him to fully be working on Disney stuff to make sure that the transition of the Fox properties goes smoothly. But Disney is the one that ends negotiations, not Sony.
5.) Someone leaks the breakdown of negotiations to the press. No one is really clear on who started the leaking, but once the leak is out there, things blow up, probably bigger than whichever company that leaked anticipated. Sony puts out that statement, in an attempt to make it clear that Disney is the one that stopped talking and that they're willing to negotiate. And both sides start talking to the press, trying to get their full side of the story out there. Variety actually hints that the leak is a negotiation tactic from Sony not necessarily to get public opinion on their side (in which case it backfired, tremendously), but to get Disney back to the table at all after they'd left. But right now we have Sony and Disney basically airing out their negotiating points in public instead of actually talking to each other about them, and Sony publicly saying the deal is dead but they're willing to come back while Disney says nothing (which can only really last until this weekend, as they're gonna have to say something to the press about it at D23).
At this point, nothing is set in stone, and everyone can come back to the table at any point before another Spider-Man movie goes into full production. But it'll take both sides getting over whatever hurt feelings and bruised egos may have happened over the past few days/months and hammering out a deal that it doesn't really seem like they were that far apart on. Because if they don't, both sides are probably leaving $100M+ on the table (though Sony needs that money more than Disney does).