Owlcat Games introduced another bug fixing patch to Pathfinder: Wrath of the Righteous, fixing some of the most significant bugs in the game.
Kingmaker may have been a mess on release but Pathfinder: Wrath of the Righteous had much better execution and game-breaking bugs weren't as frequent. That said, some of them were squashed in the opening weeks of release and Owlcat Games are not about to slow down.
The mini patch from September 15, 2021, may not have been a big download itself but it fixed some of the biggest bugs in the game. There are Act 4 spoilers ahead so think twice if you want to read on.
Most notably, those who finally gained enough reputation to meet Nocticula face to face found the Lady in Shadow stood them up. This was not intentional though as she didn't have much choice in the matter - this happened strictly because of a bug. This was fixed and should no longer mess with the players' progress.
While not game-breaking in the sense of preventing progress, Demon players could not respec. This annoyance is also out of the way so go ham with your build testing.
Unfortunately, this fix is not retroactive so if you retrained in Act 2, you will need to load a save before you retrained.