WTF is Dark Outlaw? Sonys dark passenger?
Dark Outlaw is a new studio from LA leaded by the ex-Deviation and ex-CoD Zombies head plus many other ex-several top tier shooters and/or ex-top tier GaaS of other types (many of them coming from Deviation and CoD too).
what was wrong with it in the leaks?
Nothing, it's just people who thinks games in pre-alpha stage look as good, are as complete and are as polished as released games.
They learned what exactly? Initiative is up and continue running - no change from before.
MLB, GT7, Helldivers 2 and Destiny 2 must have provided enough money to pay the budget of all the games of the dozen IPs with GaaS, including the couple ones that failed after launch, the cancelled ones and the non-greenlighted ones. And this is having half a dozen to be released, some of them like Marathon or Marvel Tokon with huge potential.
So already is very successful and wouldn't make sense to change it. Regarding lessons learnt, every time a game company releases, cancels or shut downs a game, they make a deep and extensive post mortem analysis and it is shared (at least a short recap) with the other teams within the company. For that postmortem they analyze all the key metrics, processes and performance not only of the game itself, but in all areas or departments of the project.
Normally the biggest lessons to learn stuff and improve comes from the things that didn't work (even in successful games) because it means something they assumed was wrong. So they investigate what failed and how to improve it. Regarding the things that did work (even in failed games) normally don't help a lot to them to learn and improve because it just validates that their way of doing these things works, sometimes that normally they already knew it.
As an example, even if Helldivers 2 has been a huge success there were things that failed, and took note to improve either there or in other projects. And there were things that worked very well, so other games can apply. Same goes with Concord, there were things that worked and other ones that didn't so they learnt from that too to improve other projects.
These lessons may lead to improvements or even huge changes in other projects that were having the same mistakes, or in some rare case a cancellation when combined with other factors. But well, it's pretty stupid to assume that because an arena hero shooter failed they're going to cancel over a half a dozen other games including stuff as different as a fighting game or a mixture of MOBA, smash bros like, platformer, life simes and whatever frog type games is.