About the reveal about Shigaraki this chapter: I say it once and I say it again, revealing new information that changes the context of past events is not retconing! It is literally a fundamental part of story telling!
Sometimes, I feel like people who say things like that just want to be haters to the story but try to sound "technical" about it.
Before, we really only had that one flashback of Tenko's childhood. If anything, this chapter cleared up a thought I had for a while.
I mentioned it just now in another ask, but I'll say it again.
I always wondered if AFO already knew about the Shimura family. It would make sense if he does. He is evil and one of his own worse enemies is Nana. Man rules from the shadows. He has followers! No doubt he was keeping an eye on them since Kotaro was a child. Come on.