Here's what we know about this booking disaster. Mind you, it's all mostly from Unreal so who knows how much of it is WWE lying

>John Cena starts talking to WWE about a retirement tour all the way back in 2023, this is when Vince is still in charge
>John says he can clear out his schedule to do a full year for WWE. WWE tells him they only need him for 36 appearances for some reason.
>Announces it in 2024. By this point they must have already have some vague plans on what was going to happen
>Ticket sales for EC aren't selling, so TKO gets the Rock to come in. Rock says he will only show up if there is a major angle otherwise it would be a waste. WWE agrees
>Rock's idea is for Cody to turn heel, but there's other suggestions too. Someone throws out John Cena turning heel. They go with this literally on the fly, abandoning the previous plans they made
>Travis Scott's agent knows someone at TKO so they get him involved
>At this point, something fell through backstage. On Cody's podcast, John talks about how there were actually in fact plans up to SummerSlam but it didn't work out. This portion of the interview is heavily edited, implying there's NDAs in place
>They abandon the heel turn abruptly because John says there was no time to do a redemption arc properly and fuck it, let's stop wasting the retirement tour

Basically, John is throwing Rock under the bus for the entire thing.